Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Allowance for credit losses on debt securities held to maturity	$ (15,017)	$ 0
Debt securities held to maturity, estimated fair value	$ 9,078,298	$ 6,921,158
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, liquidation preference (in dollars per share)	$ 200,000	$ 200,000
Preferred stock, number of shares authorized	30,000,000	30,000,000
Preferred stock, number of shares issued	1,150	1,150
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, number of shares authorized	300,000,000	300,000,000
Common stock, number of shares issued	222,963,891	222,963,891