Loans - Summary of Aging of Recorded Investment in Past Due Portfolio Loans by Portfolio Class and Category (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and Leases Receivable, Gross	$ 4,275,761	$ 4,097,050
Non-Covered Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	5,174	10,828
90 or More Days Past Due	9,585	2,715
Total Past Due	14,759	13,543
Current	4,200,237	4,009,353
Loans and Leases Receivable, Gross	4,214,996	4,022,896
Total	4,216,081	4,024,221
Non-Covered Loans | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	2,180	7,882
90 or More Days Past Due	8,070	1,770
Total Past Due	10,250	9,652
Current	2,027,790	1,909,068
Total	2,038,040	1,918,720
Non-Covered Loans | CRE - investor owned
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	1,141	934
90 or More Days Past Due	0	0
Total Past Due	1,141	934
Current	818,286	768,341
Total	819,427	769,275
Non-Covered Loans | CRE - owner occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	958	0
90 or More Days Past Due	484	0
Total Past Due	1,442	0
Current	591,696	554,589
Total	593,138	554,589
Non-Covered Loans | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	0	76
90 or More Days Past Due	0	0
Total Past Due	0	76
Current	300,117	303,015
Total	300,117	303,091
Non-Covered Loans | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	895	1,529
90 or More Days Past Due	1,031	945
Total Past Due	1,926	2,474
Current	316,129	338,838
Total	318,055	341,312
Non-Covered Loans | Consumer and other
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	0	407
90 or More Days Past Due	0	0
Total Past Due	0	407
Current	146,219	135,502
Loans and Leases Receivable, Gross	146,219	135,909
Total	$ 147,304	$ 137,234