Consolidated Balance Sheet (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Pledged securities that can be sold or repledged	$ 2,133,492	$ 2,136,712
Investment securities, available for sale, amortized cost	11,937,326	12,138,636
Investment securities, held to maturity, fair value	2,769,343	2,864,147
Other, fair value	$ 536,062	$ 554,059
Preferred stock, par value	$ 1.00	$ 1.00
Preferred stock, shares authorized	1,000,000	1,000,000
Common stock, par value	$ 0.50	$ 0.50
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	159,963,737	159,563,512
Common stock issuable, shares	33,391	36,644
Treasury stock, shares	841,082
Series A and Series C [Member]
Preferred stock, shares issued	731,500	731,500
Preferred stock, shares outstanding	731,500	731,500
Preferred stock, liquidation preference per share	$ 1,000	$ 1,000
Series D Preferred Stock [Member]
Preferred stock, shares issued	50,000	50,000
Preferred stock, shares outstanding	50,000	50,000
Preferred stock, liquidation preference per share	$ 10,000	$ 10,000