Restructuring Charges (Details) (USD $)	12 Months Ended
	Dec. 31, 2012 branches	Dec. 31, 2011 branches	Dec. 31, 2010
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 5,412,000	$ 30,665,000	$ 5,538,000
Number of branches closed	10	31
Premises and equipment transferred to other assets held for sale	3,800,000	17,800,000
Impairment charges	2,000,000	6,600,000
Gain on sale of assets held for sale	622,000	929,000	0
Proceeds from sale of assets held-for-sale	5,800,000	5,100,000
Assets held-for-sale, at carrying value	3,600,000
Accrued liabilities	$ 728,000
Minimum retention period (days)	60