Annual report pursuant to Section 13 and 15(d)

Fair Value of Financial Instruments (Details)

v3.8.0.1
Fair Value of Financial Instruments (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Repurchase agreements $ 19,451,207 $ 8,865,184
Long-term Federal Home Loan Bank Advances 1,215,024  
Maturity Over One Year [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Repurchase agreements $ 112,500 $ 0