Noninterest Income and Expenses (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								9 Months Ended
	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Sep. 30, 2012	Sep. 30, 2011
Components of other noninterest income
Service charges on deposit accounts	$ 3,617					$ 3,769			$ 10,788	$ 10,899
ATM and interchange fees	1,877					1,780			5,722	5,201
Other service fees	567					460			1,740	1,303
Mortgage banking service fees	403					375			1,154	1,106
Change in value of mortgage servicing rights	(681)					(800)			(1,513)	(1,022)
Total service charges and fees	5,783					5,584			17,890	17,487
Gain on sale of loans	1,430					598			4,317	1,818
Commissions on sale of non-deposit investment products	803					542			2,464	1,550
Increase in cash value of life insurance	450					450			1,350	1,350
Change in indemnification asset	(94)					(289)			215	1,547
Gain on sale of foreclosed assets	419					82			364	467
Sale of customer checks	90					72			256	198
Lease brokerage income	80					43			228	171
Gain (loss) on disposal of fixed assets	(16)								(404)	(15)
Commission rebates	(17)					(16)			(51)	(49)
Gain on life insurance death benefit									600
Bargain purchase gain on acquisition						7,575			600
Other	199					82			740	225
Total other noninterest income	3,344					9,139			10,079	14,837
Total noninterest income	$ 9,127	$ 10,577	$ 8,265	$ 10,489	$ 8,029	$ 14,723	$ 8,251	$ 9,350	$ 27,969	$ 32,324