Consolidated Balance Sheet (Unaudited) (Parenthetical) (USD $) In Thousands, except Share data	Sep. 30, 2011	Dec. 31, 2010
Assets
Pledged securities that can be sold or repledged	$ 1,876,435	$ 1,937,817
Investment securities, available for sale, amortized cost	5,717,180	5,494,377
Investment securities, held to maturity, fair value	1,097,215	1,225,253
Other debt securities, fair value	$ 376,082	$ 412,709
Shareholders' equity
Preferred stock, par value	$ 1.00	$ 1.00
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	381,500	778,000
Preferred stock, shares outstanding	50,000
Preferred stock, liquidation preference per share	$ 1,000	$ 1,000
Liquidation preference, per share	$ 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	125,610,181	120,396,611
Common stock issuable, shares	68,107	71,345
Treasury stock - common, shares		693,974