Income Taxes - Significant Components of The Company's Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Deferred tax assets
Allowance for loan losses	$ 20,421	$ 19,934	$ 21,418
Loans	25,585	23,240	24,299
Deferred compensation	10,857	11,254	12,368
Securities	2,573	2,439	2,346
Net unrealized losses on securities - OCI	1,942	10,096	4,016
Impairment of assets	2,383	2,512	3,877
Federal and State net operating loss carryforwards	3,338	2,867	3,113
Intangibles	0	1,247	1,012
Other	7,319	3,463	7,958
Total deferred tax assets	74,418	77,052	80,407
Deferred tax liabilities
FDIC loss-share indemnification asset	0	0	1,939
Investment in partnerships	946	1,556	2,001
Intangibles	428	0	0
Fixed assets	1,429	2,517	2,598
Mortgage servicing rights	3,360	3,360	3,589
Junior subordinated debt	3,620	4,111	4,128
Other	1,770	2,876	4,294
Total deferred tax liabilities	11,553	14,420	18,549
Net deferred tax assets	$ 62,865	$ 62,632	$ 61,858