Income Taxes - (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Deferred tax assets
Allowance for loan losses	$ 19,999	$ 19,934	$ 20,787
Loans	21,159	23,240	29,042
Deferred compensation	9,120	11,254	10,786
Securities	2,440	2,439	2,572
Net unrealized losses on securities - OCI	8,209	10,096	4,876
Impairment of assets	1,962	2,512	3,280
Federal and State net operating loss carryforwards	3,354	2,867	5,124
Intangibles	1,229	1,247	0
Other	2,834	3,463	4,957
Gross deferred tax assets	70,306	77,052	81,424
Valuation allowance on state net operating loss carryforwards	0	0	0
Total deferred tax assets	70,306	77,052	81,424
Deferred tax liabilities
FDIC loss-share indemnification asset	0	0	1,807
Investment in partnerships	1,414	1,556	2,343
Core deposit intangible	0	0	2,992
Fixed assets	2,248	2,517	924
Mortgage servicing rights	3,359	3,360	3,977
Junior subordinated debt	4,058	4,111	4,234
Other	2,428	2,876	4,855
Total deferred tax liabilities	13,507	14,420	21,132
Net deferred tax assets	$ 56,799	$ 62,632	$ 60,292