Quarterly report pursuant to Section 13 or 15(d)

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

v3.10.0.1
Schedule of Available-for-sale Securities Reconciliation (Details) - USD ($)
$ in Thousands
Sep. 30, 2018
Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]    
Principal/Current Face $ 35,068,573 $ 29,396,680
Unamortized Premium 1,362,059 1,370,959
Accretable Purchase Discount 723,571 700,671
Credit Reserve Purchase Discount 1,194,749 653,613
Amortized Cost 26,087,090 20,856,658
Unrealized Gain 579,177 544,198
Unrealized Loss 727,351 180,037
Available-for-sale securities, at fair value 25,938,916 21,220,819
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]    
Debt Securities, Available-for-sale [Line Items]    
Principal/Current Face 24,795,205 20,023,621
Unamortized Premium 1,284,982 1,302,535
Accretable Purchase Discount 38,957 24,638
Credit Reserve Purchase Discount 0 0
Amortized Cost 22,812,501 18,359,746
Unrealized Gain 22,097 53,104
Unrealized Loss 715,652 174,125
Available-for-sale securities, at fair value 22,118,946 18,238,725
Mortgage-backed Securities, Issued by Private Enterprises [Member]    
Debt Securities, Available-for-sale [Line Items]    
Principal/Current Face 10,273,368 9,373,059
Unamortized Premium 77,077 68,424
Accretable Purchase Discount 684,614 676,033
Credit Reserve Purchase Discount 1,194,749 653,613
Amortized Cost 3,274,589 2,496,912
Unrealized Gain 557,080 491,094
Unrealized Loss 11,699 5,912
Available-for-sale securities, at fair value 3,819,970 2,982,094
Interest-Only-Strip [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]    
Debt Securities, Available-for-sale [Line Items]    
Principal/Current Face 3,228,729 2,941,772
Unamortized Premium 218,997 223,289
Accretable Purchase Discount 0 0
Credit Reserve Purchase Discount 0 0
Amortized Cost 218,997 223,289
Unrealized Gain 14,812 10,955
Unrealized Loss 50,244 39,156
Available-for-sale securities, at fair value 183,565 195,088
Interest-Only-Strip [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member]    
Debt Securities, Available-for-sale [Line Items]    
Principal/Current Face 5,196,493 5,614,925
Unamortized Premium 70,511 65,667
Accretable Purchase Discount 0 0
Credit Reserve Purchase Discount 0 0
Amortized Cost 70,511 65,667
Unrealized Gain 4,264 2,163
Unrealized Loss 2,606 2,746
Available-for-sale securities, at fair value 72,169 65,084
Fixed Income Securities [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]    
Debt Securities, Available-for-sale [Line Items]    
Principal/Current Face 21,566,476 17,081,849
Unamortized Premium 1,065,985 1,079,246
Accretable Purchase Discount 38,957 24,638
Credit Reserve Purchase Discount 0 0
Amortized Cost 22,593,504 18,136,457
Unrealized Gain 7,285 42,149
Unrealized Loss 665,408 134,969
Available-for-sale securities, at fair value 21,935,381 18,043,637
Fixed Income Securities [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member]    
Debt Securities, Available-for-sale [Line Items]    
Principal/Current Face 5,076,875 3,758,134
Unamortized Premium 6,566 2,757
Accretable Purchase Discount 684,614 676,033
Credit Reserve Purchase Discount 1,194,749 653,613
Amortized Cost 3,204,078 2,431,245
Unrealized Gain 552,816 488,931
Unrealized Loss 9,093 3,166
Available-for-sale securities, at fair value $ 3,747,801 $ 2,917,010