Loans - Summary of Allowance for Loan Losses by Portfolio Class and Category (Details) - Portfolio loans, net $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2017	$ 38,166
Provision (provision reversal) for loan losses	1,871
Losses charged off	(1,035)
Recoveries	1,261
Balance at March 31, 2018	40,263
Commercial and industrial
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2017	26,406
Provision (provision reversal) for loan losses	780
Losses charged off	(732)
Recoveries	956
Balance at March 31, 2018	27,410
CRE - investor owned
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2017	3,890
Provision (provision reversal) for loan losses	648
Losses charged off	0
Recoveries	8
Balance at March 31, 2018	4,546
CRE - owner occupied
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2017	3,308
Provision (provision reversal) for loan losses	190
Losses charged off	0
Recoveries	4
Balance at March 31, 2018	3,502
Construction and land development
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2017	1,487
Provision (provision reversal) for loan losses	35
Losses charged off	0
Recoveries	206
Balance at March 31, 2018	1,728
Residential real estate
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2017	2,237
Provision (provision reversal) for loan losses	259
Losses charged off	(254)
Recoveries	73
Balance at March 31, 2018	2,315
Consumer and other
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2017	838
Provision (provision reversal) for loan losses	(41)
Losses charged off	(49)
Recoveries	14
Balance at March 31, 2018	$ 762