Quarterly report pursuant to Section 13 or 15(d)

Available-for-sale Securities Classified by Rate Type (Details)

v3.20.1
Available-for-sale Securities Classified by Rate Type (Details) - USD ($)
$ in Thousands
Mar. 31, 2020
Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]    
Adjustable Rate $ 37,117 $ 3,358,871
Fixed Rate 17,695,942 28,047,457
Available-for-sale securities, at fair value 17,733,059 31,406,328
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]    
Debt Securities, Available-for-sale [Line Items]    
Adjustable Rate 13,820 14,584
Fixed Rate 17,692,839 27,763,471
Available-for-sale securities, at fair value 17,706,659 27,778,055
Mortgage-backed Securities, Issued by Private Enterprises [Member]    
Debt Securities, Available-for-sale [Line Items]    
Adjustable Rate 23,297 3,344,287
Fixed Rate 3,103 283,986
Available-for-sale securities, at fair value $ 26,400 $ 3,628,273