Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Securities held-to-maturity ,fair value	$ 4,114,595	$ 3,948,706
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	3,000,000	3,000,000
Common stock par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	93,644,633	93,623,090
Treasury stock ,shares	1,910,786	3,241,555
Series A Preferred Stock [Member]
Preferred stock, shares issued	0	28,939
Preferred stock, shares outstanding	0	28,939
Series E Preferred Stock [Member]
Preferred stock, shares issued	5,060	5,060
Preferred stock, shares outstanding	5,060	5,060