Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $)	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2010
Investment Securities:
Securities, fair value	$ 1,491,048,000	$ 469,421,000	$ 118,155,000
Shareholders' Equity
Preferred stock, no par value
Preferred stock, shares authorized	5,000,000	5,000,000	5,000,000
Preferred stock, shares issued	300,000	300,000	300,000
Preferred stock, shares outstanding	300,000	300,000	300,000
Preferred stock, redemption value	$ 300,000,000	$ 300,000,000	$ 300,000,000
Common stock, no par value
Common stock, shares authorized	105,000,000	105,000,000	105,000,000
Common stock, shares issued	40,034,943	39,716,714	39,707,068
Common stock, shares outstanding	40,034,943	39,716,714	39,707,068