Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Assets:
Mortgage servicing rights	$ 4,116	$ 3,487
Level 1
Assets:
Investment securities available-for-sale	1,507	1,524
Level 2
Assets:
Investment securities available-for-sale	568,290	295,928
Loans held-for-sale	9,571	12,806
Level 3
Assets:
Investment securities available-for-sale	10,089	10,112
Total
Assets:
Investment securities available-for-sale		307,564
Recurring basis | Level 1 | U.S. Treasury
Assets:
Investment securities available-for-sale	1,507	1,524
Recurring basis | Level 2
Assets:
Loans held-for-sale	9,571	12,806
Total financial assets	579,777	311,993
Liabilities:
Liabilities at fair value	1,354	3,202
Recurring basis | Level 2 | Interest rate swap agreements net of swap credit valuation
Assets:
Other assets	1,349	3,152
Liabilities:
Other liabilities	1,349	3,152
Recurring basis | Level 2 | Mortgage banking derivatives
Assets:
Other assets	567	107
Recurring basis | Level 2 | Interest rate lock commitments to borrowers
Liabilities:
Other liabilities	5	50
Recurring basis | Level 2 | U.S. government agencies
Assets:
Investment securities available-for-sale	49,850	43,398
Recurring basis | Level 2 | U.S. government agency mortgage-backed
Assets:
Investment securities available-for-sale	128,738	154,007
Recurring basis | Level 2 | States and political subdivisions
Assets:
Investment securities available-for-sale	15,723	13,671
Recurring basis | Level 2 | Corporate bonds
Assets:
Investment securities available-for-sale	36,886	31,389
Recurring basis | Level 2 | Collateralized mortgage obligations
Assets:
Investment securities available-for-sale	169,600	25,122
Recurring basis | Level 2 | Asset-backed securities
Assets:
Investment securities available-for-sale	167,493	28,341
Recurring basis | Level 3
Assets:
Mortgage servicing rights	4,116	3,487
Total financial assets	14,158	13,519
Recurring basis | Level 3 | Interest rate swap agreements net of swap credit valuation
Assets:
Other assets	(47)	(80)
Recurring basis | Level 3 | States and political subdivisions
Assets:
Investment securities available-for-sale	132	138
Recurring basis | Level 3 | Collateralized debt obligations
Assets:
Investment securities available-for-sale	9,957	9,974
Recurring basis | Total
Assets:
Loans held-for-sale	9,571	12,806
Mortgage servicing rights	4,116	3,487
Total financial assets	595,442	327,036
Liabilities:
Liabilities at fair value	1,354	3,202
Recurring basis | Total | Interest rate swap agreements net of swap credit valuation
Assets:
Other assets	1,302	3,072
Liabilities:
Other liabilities	1,349	3,152
Recurring basis | Total | Mortgage banking derivatives
Assets:
Other assets	567	107
Recurring basis | Total | Interest rate lock commitments to borrowers
Liabilities:
Other liabilities	5	50
Recurring basis | Total | U.S. Treasury
Assets:
Investment securities available-for-sale	1,507	1,524
Recurring basis | Total | U.S. government agencies
Assets:
Investment securities available-for-sale	49,850	43,398
Recurring basis | Total | U.S. government agency mortgage-backed
Assets:
Investment securities available-for-sale	128,738	154,007
Recurring basis | Total | States and political subdivisions
Assets:
Investment securities available-for-sale	15,855	13,809
Recurring basis | Total | Corporate bonds
Assets:
Investment securities available-for-sale	36,886	31,389
Recurring basis | Total | Collateralized mortgage obligations
Assets:
Investment securities available-for-sale	169,600	25,122
Recurring basis | Total | Asset-backed securities
Assets:
Investment securities available-for-sale	167,493	28,341
Recurring basis | Total | Collateralized debt obligations
Assets:
Investment securities available-for-sale	$ 9,957	$ 9,974