Annual report pursuant to Section 13 and 15(d)

Schedule of Available-for-Sale Securities Reconciliation (Details)

v2.4.1.9
Schedule of Available-for-Sale Securities Reconciliation (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Face Value $ 17,713,427two_AvailableForSaleSecuritiesFaceValue $ 16,393,943two_AvailableForSaleSecuritiesFaceValue
Available-for-sale Securities, Unamortized Premium 676,641two_AvailableForSaleSecuritiesUnamortizedPremium 621,279two_AvailableForSaleSecuritiesUnamortizedPremium
Available-for-sale Securities, Designated Credit Reserve (927,605)two_AvailableForSaleSecuritiesDesignatedCreditReserve (1,234,449)two_AvailableForSaleSecuritiesDesignatedCreditReserve
Available-for-sale Securities, Net, Unamortized (3,977,150)two_AvailableForSaleSecuritiesNetUnamortized (3,968,781)two_AvailableForSaleSecuritiesNetUnamortized
Available-for-sale Securities, Amortized Cost Basis 13,485,313us-gaap_AvailableForSaleSecuritiesAmortizedCost 11,811,992us-gaap_AvailableForSaleSecuritiesAmortizedCost
Available-for-sale Securities, Unrealized Gains 891,820two_AvailableForSaleSecuritiesUnrealizedGains 697,779two_AvailableForSaleSecuritiesUnrealizedGains
Available-for-sale Securities, Unrealized Losses (36,031)two_AvailableForSaleSecuritiesUnrealizedLosses (253,044)two_AvailableForSaleSecuritiesUnrealizedLosses
Available-for-sale securities, at fair value 14,341,102us-gaap_AvailableForSaleSecurities 12,256,727us-gaap_AvailableForSaleSecurities
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Face Value 13,421,555two_AvailableForSaleSecuritiesFaceValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember 		11,919,590two_AvailableForSaleSecuritiesFaceValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Available-for-sale Securities, Unamortized Premium 676,641two_AvailableForSaleSecuritiesUnamortizedPremium
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember 		621,279two_AvailableForSaleSecuritiesUnamortizedPremium
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Available-for-sale Securities, Designated Credit Reserve 0two_AvailableForSaleSecuritiesDesignatedCreditReserve
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember 		0two_AvailableForSaleSecuritiesDesignatedCreditReserve
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Available-for-sale Securities, Net, Unamortized (3,009,782)two_AvailableForSaleSecuritiesNetUnamortized
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember 		(2,897,222)two_AvailableForSaleSecuritiesNetUnamortized
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Available-for-sale Securities, Amortized Cost Basis 11,088,414us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember 		9,643,647us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Available-for-sale Securities, Unrealized Gains 238,291two_AvailableForSaleSecuritiesUnrealizedGains
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember 		102,600two_AvailableForSaleSecuritiesUnrealizedGains
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Available-for-sale Securities, Unrealized Losses (34,388)two_AvailableForSaleSecuritiesUnrealizedLosses
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember 		(248,838)two_AvailableForSaleSecuritiesUnrealizedLosses
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Available-for-sale securities, at fair value 11,292,317us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember 		9,497,409us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Mortgage-backed Securities, Issued by Private Enterprises [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Face Value 4,291,872two_AvailableForSaleSecuritiesFaceValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember 		4,474,353two_AvailableForSaleSecuritiesFaceValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember
Available-for-sale Securities, Unamortized Premium 0two_AvailableForSaleSecuritiesUnamortizedPremium
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember 		0two_AvailableForSaleSecuritiesUnamortizedPremium
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember
Available-for-sale Securities, Designated Credit Reserve (927,605)two_AvailableForSaleSecuritiesDesignatedCreditReserve
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember 		(1,234,449)two_AvailableForSaleSecuritiesDesignatedCreditReserve
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember
Available-for-sale Securities, Net, Unamortized (967,368)two_AvailableForSaleSecuritiesNetUnamortized
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember 		(1,071,559)two_AvailableForSaleSecuritiesNetUnamortized
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember
Available-for-sale Securities, Amortized Cost Basis 2,396,899us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember 		2,168,345us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember
Available-for-sale Securities, Unrealized Gains 653,529two_AvailableForSaleSecuritiesUnrealizedGains
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember 		595,179two_AvailableForSaleSecuritiesUnrealizedGains
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember
Available-for-sale Securities, Unrealized Losses (1,643)two_AvailableForSaleSecuritiesUnrealizedLosses
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember 		(4,206)two_AvailableForSaleSecuritiesUnrealizedLosses
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember
Available-for-sale securities, at fair value $ 3,048,785us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember 		$ 2,759,318us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember