Portfolio Loans - Summary of Aging of Recorded Investment in Past Due Portfolio Loans by Portfolio Class and Category (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, including unearned loan fees	$ 4,350,001	$ 4,097,050
Non-Covered Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	1,602	10,828
Financing Receivable, Recorded Investment, 90 Days Past Due	12,158	2,715
Total Past Due	13,760	13,543
Current	4,289,840	4,009,353
Total	4,305,626	4,024,221
Loans, including unearned loan fees	4,303,600	4,022,896
Non-Covered Loans | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	66	7,882
Financing Receivable, Recorded Investment, 90 Days Past Due	10,257	1,770
Total Past Due	10,323	9,652
Current	2,110,685	1,909,068
Total	2,121,008	1,918,720
Non-Covered Loans | CRE - investor owned
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	529	934
Financing Receivable, Recorded Investment, 90 Days Past Due	127	0
Total Past Due	656	934
Current	843,072	768,341
Total	843,728	769,275
Non-Covered Loans | CRE - owner occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	292	0
Financing Receivable, Recorded Investment, 90 Days Past Due	565	0
Total Past Due	857	0
Current	603,641	554,589
Total	604,498	554,589
Non-Covered Loans | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	6	76
Financing Receivable, Recorded Investment, 90 Days Past Due	0	0
Total Past Due	6	76
Current	330,091	303,015
Total	330,097	303,091
Non-Covered Loans | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	709	1,529
Financing Receivable, Recorded Investment, 90 Days Past Due	897	945
Total Past Due	1,606	2,474
Current	297,338	338,838
Total	298,944	341,312
Non-Covered Loans | Consumer and other
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	0	407
Financing Receivable, Recorded Investment, 90 Days Past Due	312	0
Total Past Due	312	407
Current	105,013	135,502
Total	107,351	137,234
Loans, including unearned loan fees	$ 105,325	$ 135,909