Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Security held-to-maturity, fair value	$ 4,456,350	$ 4,125,125
LHFS, at fair value option	$ 20,888	$ 60,260
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Preferred stock, shares authorized	3,000,000	3,000,000
Common stock par value (in usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued		93,651,601
Treasury stock, shares	1,658,526	1,899,502
Series E Preferred Stock [Member]
Preferred stock, shares issued		5,060
Preferred Stock, Shares Outstanding		5,060
Series F Preferred Stock [Member]
Preferred stock, shares issued	6,000
Preferred Stock, Shares Outstanding	6,000