Consolidated Balance Sheets Parenthetical - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Investment securities held to maturity, estimated fair value	$ 1,244,121	$ 1,275,963
Preferred stock, par value	$ 0.01	$ 0
Preferred stock, liquidation preference (in dollars per share)	$ 200,000	$ 0
Preferred stock, number of shares authorized	30,000,000	0
Preferred stock, number of shares issued	1,150	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, number of shares authorized	300,000,000	300,000,000
Common stock, number of shares issued	222,950,751	222,950,751