Consolidated Balance Sheets Parenthetical (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Mar. 31, 2013 Series A Preferred Stock [Member]	Dec. 31, 2012 Series A Preferred Stock [Member]	Mar. 31, 2012 Series A Preferred Stock [Member]	Mar. 31, 2013 Series B Preferred Stock [Member]	Dec. 31, 2012 Series B Preferred Stock [Member]	Mar. 31, 2012 Series B Preferred Stock [Member]	Mar. 31, 2013 Series A Non-Cumulative Perpetual Preferred Stock [Member]	Dec. 31, 2012 Series A Non-Cumulative Perpetual Preferred Stock [Member]	Jun. 30, 2012 Series A Non-Cumulative Perpetual Preferred Stock [Member]
Common Stock, No Par Value	$ 0	$ 0	$ 0
Common Stock, Shares Authorized	300,000,000	300,000,000	300,000,000
Common Stock, Shares, Issued	115,121,731	115,121,731	115,121,731
Preferred Stock, No Par Value	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0
Preferred Stock, Shares Outstanding				0	0	0	0	0	0	100,000	0	0
Preferred Stock, Shares Authorized	7,000,000	7,000,000	7,000,000	800,000	800,000	800,000	220,000	220,000	220,000	115,000	0	0
Preferred Stock, Shares Subscribed but Unissued	7,000,000	7,000,000	7,000,000
Treasury Stock, Shares	5,375,905	5,935,169	5,472,915
Expected Reimbursement for Losses Incurred Covered Other Real Estate	$ 44,000	$ 732,000	$ 49,000
Covered Loans Loss Share Receivable	$ 95,593,000	$ 171,136,000	$ 113,734,000