CONSOLIDATED BALANCE SHEET (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Statement Of Financial Position [Abstract]
Pledged securities that can be sold or repledged	$ 1,761,978	$ 1,801,842
Investment securities, available for sale, amortized cost	4,288,994	4,643,070
Investment securities, held to maturity, fair value	910,783	976,883
Other, fair value	$ 300,890	$ 302,648
Preferred stock, par value	$ 1.00	$ 1.00
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued and outstanding Series A & C	381,500	381,500
Preferred stock, shares issued and outstanding Series D	50,000	50,000
Preferred stock, liquidation preference per share Series A & C	$ 1,000	$ 1,000
Preferred stock, liquidation preference per share Series D	$ 10,000	$ 10,000
Common stock, par value	$ 0.50	$ 0.50
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	128,952,578	128,176,912
Common stock issuable, shares	46,552	57,409