Loans - Summary of Allowance for Loan Losses by Portfolio Class and Category (Details) - USD ($) $ in Thousands	3 Months Ended
Jun. 30, 2019	Mar. 31, 2019
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2018		$ 43,476
Balance	$ 43,822
Portfolio loans, net
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2018	41,945	42,295
Provision (provision reversal) for loan losses	1,960	1,476
Losses charged off	(1,890)	(2,250)
Recoveries	920	424
Balance	42,935	41,945
Portfolio loans, net \| Commercial and industrial
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2018	28,660	29,039
Provision (provision reversal) for loan losses	1,781	1,445
Losses charged off	(1,380)	(1,853)
Recoveries	32	29
Balance	29,093	28,660
Portfolio loans, net \| CRE - investor owned
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2018	5,339	4,683
Provision (provision reversal) for loan losses	364	769
Losses charged off	(431)	(120)
Recoveries	52	7
Balance	5,324	5,339
Portfolio loans, net \| CRE - owner occupied
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2018	3,774	4,239
Provision (provision reversal) for loan losses	591	(431)
Losses charged off	0	(36)
Recoveries	6	2
Balance	4,371	3,774
Portfolio loans, net \| Construction and land development
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2018	1,699	1,987
Provision (provision reversal) for loan losses	(216)	(252)
Losses charged off	0	(45)
Recoveries	489	9
Balance	1,972	1,699
Portfolio loans, net \| Residential real estate
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2018	1,625	1,616
Provision (provision reversal) for loan losses	(345)	(288)
Losses charged off	(26)	(67)
Recoveries	124	364
Balance	1,378	1,625
Portfolio loans, net \| Consumer and other
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2018	848	731
Provision (provision reversal) for loan losses	(215)	233
Losses charged off	(53)	(129)
Recoveries	217	13
Balance	$ 797	$ 848

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

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