Loans and Asset Quality Information (Details 6) (USD $) In Thousands, unless otherwise specified	9 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Impaired loans at period end	$ 163,499	$ 139,718	$ 140,976
Average amount of impaired loans for period	148,255	155,146	152,312
Impaired loans with related allowance - Related Allowance	13,484	7,716	10,910
Impaired loans with no related allowance - Recorded Investment	74,745	79,815	79,423
Non-covered
Impaired loans at period end	107,935	86,270	85,286
Average amount of impaired loans for period	92,027	89,957	89,023
Impaired loans with related allowance - Related Allowance	9,410	5,429	5,804
Impaired loans with no related allowance - Recorded Investment	34,150	35,897	35,721
Covered
Impaired loans at period end	55,564	53,448	55,690
Average amount of impaired loans for period	56,228	65,189	63,289
Impaired loans with related allowance - Related Allowance	4,074	2,287	5,106
Impaired loans with no related allowance - Recorded Investment	$ 40,595	$ 43,918	$ 43,702