Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Securities held to maturity, fair value		$ 3,181,275	$ 3,218,379
Loans held for sale, fair value	[1]	28,213	56,458
Unearned income on loans		$ 39,202	$ 50,680
Preferred stock, par value (in dollars per share)		$ 0.01	$ 0.01
Preferred stock, liquidation preference per share (in dollars per share)		$ 1,000	$ 1,000
Preferred stock, shares authorized		20,000,000	20,000,000
Preferred stock, shares issued		110,877	110,877
Common stock, par value (in dollars per share)		$ 0.01	$ 0.01
Common stock, shares authorized		500,000,000	500,000,000
Common stock, shares issued		326,064,004	325,095,055
Treasury stock, shares		1,805,662	1,629,915

[1] Amount represents loans for which we have elected the fair value option. See Note 18.