Quarterly report pursuant to Section 13 or 15(d)

Fair Value of Financial Instruments (Details)

v3.10.0.1
Fair Value of Financial Instruments (Details) - USD ($)
$ in Thousands
Sep. 30, 2018
Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Repurchase agreements $ 23,806,631 $ 19,451,207
Long-term Federal Home Loan Bank Advances 50,000  
Revolving credit facilities 310,000 20,000
Maturity Over One Year [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Revolving credit facilities 290,000 0
Maturity Over One Year [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Repurchase agreements $ 200,000 $ 112,500