Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Noncovered loans:
Covered loans, loss share receivable	$ 205.7	$ 288.6
Stockholders' equity:
Preferred stock, par value	$ 0	$ 0
Preferred stock, shares authorized	7,000,000	7,000,000
Preferred stock, shares unissued	7,000,000	7,000,000
Common stock, par value	$ 0	$ 0
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	115,121,731	115,121,731
Treasury stock, shares	5,870,923	6,305,218
Series A preferred stock
Stockholders' equity:
Preferred stock, par value	$ 0	$ 0
Preferred stock, shares authorized	800,000	800,000
Preferred stock, shares outstanding	0	0
Convertible preferred stock Series B
Stockholders' equity:
Preferred stock, par value	$ 0	$ 0
Preferred stock, shares authorized	220,000	220,000
Preferred stock, shares outstanding	0	0