Loans - Summary of Aging of Recorded Investment in Past Due Portfolio Loans by Portfolio Class and Category (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Past Due [Line Items]
Loans and Leases Receivable, Gross	$ 5,149,497	$ 4,350,001
Non-Covered Loans
Financing Receivable, Past Due [Line Items]
30-89 Days Past Due	10,063	1,602
90 or More Days Past Due	16,462	12,158
Total Past Due	26,525	13,760
Current	5,019,657	4,289,840
Loans and Leases Receivable, Gross	5,046,182	4,303,600
Total	5,048,164	4,305,626
Non-Covered Loans | Commercial and industrial
Financing Receivable, Past Due [Line Items]
30-89 Days Past Due	6,682	66
90 or More Days Past Due	12,562	10,257
Total Past Due	19,244	10,323
Current	2,229,327	2,110,685
Total	2,248,571	2,121,008
Non-Covered Loans | CRE - investor owned
Financing Receivable, Past Due [Line Items]
30-89 Days Past Due	1,647	529
90 or More Days Past Due	1,096	127
Total Past Due	2,743	656
Current	1,195,565	843,072
Total	1,198,308	843,728
Non-Covered Loans | CRE - owner occupied
Financing Receivable, Past Due [Line Items]
30-89 Days Past Due	415	292
90 or More Days Past Due	155	565
Total Past Due	570	857
Current	677,476	603,641
Total	678,046	604,498
Non-Covered Loans | Construction and land development
Financing Receivable, Past Due [Line Items]
30-89 Days Past Due	41	6
90 or More Days Past Due	0	0
Total Past Due	41	6
Current	396,329	330,091
Total	396,370	330,097
Non-Covered Loans | Residential real estate
Financing Receivable, Past Due [Line Items]
30-89 Days Past Due	1,147	709
90 or More Days Past Due	2,649	897
Total Past Due	3,796	1,606
Current	392,032	297,338
Total	395,828	298,944
Non-Covered Loans | Consumer and other
Financing Receivable, Past Due [Line Items]
30-89 Days Past Due	131	0
90 or More Days Past Due	0	312
Total Past Due	131	312
Current	128,928	105,013
Loans and Leases Receivable, Gross	129,059	105,325
Total	$ 131,041	$ 107,351