Income Taxes - (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Deferred tax assets
Allowance for loan losses	$ 20,787	$ 17,430	$ 16,554
Loans	29,042	26,239	17,156
Deferred compensation	10,786	17,060	7,524
Securities	2,572	2,572	1,331
Net unrealized losses on securities - OCI	4,876	6,065	3,550
Impairment of assets	3,280	3,271	3,846
Federal and State net operating loss carryforwards	5,124	3,681	1,496
Other	4,957	4,927	1,997
Gross deferred tax assets	81,424	81,245	53,454
Valuation allowance on state net operating loss carryforwards	0	0	0
Total deferred tax assets	81,424	81,245	53,454
Deferred tax liabilities
FDIC loss-share indemnification asset	1,807	1,927	3,199
Investment in partnerships	2,343	2,507	2,600
Core deposit intangible	2,992	3,386	1,961
Fixed assets	924	673	2,947
Mortgage servicing rights	3,977	4,032	0
Subordinated debt	4,234	4,287	4,455
Other	4,855	2,364	490
Total deferred tax liabilities	21,132	19,176	15,652
Net deferred tax assets	$ 60,292	$ 62,069	$ 37,802