Loans and Asset Quality Information (Details 6) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Information related to impaired loans:
Impaired loans at period end	$ 125,098	$ 135,811	$ 106,838
Average amount of impaired loans for period	115,969	138,397	139,971
Impaired loans with related allowance - Related Allowance	9,781	16,970	8,560
Impaired loans with no related allowance - Recorded Investment	53,421	53,473	47,245
Non-covered
Information related to impaired loans:
Impaired loans at period end	63,295	80,284	57,882
Average amount of impaired loans for period	60,589	82,788	85,198
Impaired loans with related allowance - Related Allowance	5,920	11,662	5,051
Impaired loans with no related allowance - Recorded Investment	8,573	16,717	12,049
Covered
Information related to impaired loans:
Impaired loans at period end	61,803	55,527	48,956
Average amount of impaired loans for period	55,380	55,609	54,773
Impaired loans with related allowance - Related Allowance	3,861	5,308	3,509
Impaired loans with no related allowance - Recorded Investment	$ 44,848	$ 36,756	$ 35,196