Loans - Summary of Portfolio Loans Individually Evaluated for Impairment by Category (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Financing Receivable, Impaired [Line Items]
Financing Receivable, Allowance for Credit Losses	$ 43,095	$ 43,476
Portfolio loans, net
Financing Receivable, Impaired [Line Items]
Provision for Loan, Lease, and Other Losses	1,476
Unpaid Contractual Principal Balance	11,963	26,047
Recorded Investment With No Allowance	3,314	5,823
Recorded Investment With Allowance	6,293	10,922
Total Recorded Investment	9,607	16,745
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	2,914	4,453
Impaired Financing Receivable, Related Allowance	2,795	4,453
Average Recorded Investment	10,261	15,573
Financing Receivable, Allowance for Credit Losses, Write-downs	(2,250)
Financing Receivable, Allowance for Credit Losses, Recovery	424
Financing Receivable, Allowance for Credit Losses	41,945	42,295
Portfolio loans, net \| Commercial and industrial
Financing Receivable, Impaired [Line Items]
Provision for Loan, Lease, and Other Losses	1,445
Unpaid Contractual Principal Balance	9,515	21,893
Recorded Investment With No Allowance	2,168	3,294
Recorded Investment With Allowance	5,037	9,656
Total Recorded Investment	7,205	12,950
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	2,199	4,266
Impaired Financing Receivable, Related Allowance	2,199	4,266
Average Recorded Investment	7,855	13,827
Financing Receivable, Allowance for Credit Losses, Write-downs	(1,853)
Financing Receivable, Allowance for Credit Losses, Recovery	29
Financing Receivable, Allowance for Credit Losses	28,660	29,039
Portfolio loans, net \| Commercial - investor owned
Financing Receivable, Impaired [Line Items]
Provision for Loan, Lease, and Other Losses	769
Unpaid Contractual Principal Balance	1,555	553
Recorded Investment With No Allowance	271	398
Recorded Investment With Allowance	1,256	0
Total Recorded Investment	1,527	398
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	596	0
Impaired Financing Receivable, Related Allowance	596	0
Average Recorded Investment	1,527	277
Financing Receivable, Allowance for Credit Losses, Write-downs	(120)
Financing Receivable, Allowance for Credit Losses, Recovery	7
Financing Receivable, Allowance for Credit Losses	5,339	4,683
Portfolio loans, net \| Commercial - owner occupied
Financing Receivable, Impaired [Line Items]
Provision for Loan, Lease, and Other Losses	(431)
Unpaid Contractual Principal Balance	484	847
Recorded Investment With No Allowance	467	472
Recorded Investment With Allowance	0	336
Total Recorded Investment	467	808
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	119	109
Impaired Financing Receivable, Related Allowance	0	109
Average Recorded Investment	471	691
Financing Receivable, Allowance for Credit Losses, Write-downs	(36)
Financing Receivable, Allowance for Credit Losses, Recovery	2
Financing Receivable, Allowance for Credit Losses	3,774	4,239
Portfolio loans, net \| Construction and land development
Financing Receivable, Impaired [Line Items]
Provision for Loan, Lease, and Other Losses	(252)
Unpaid Contractual Principal Balance	0	0
Recorded Investment With No Allowance	0	0
Recorded Investment With Allowance	0	0
Total Recorded Investment	0	0
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0	0
Impaired Financing Receivable, Related Allowance	0	0
Average Recorded Investment	0	0
Financing Receivable, Allowance for Credit Losses, Write-downs	(45)
Financing Receivable, Allowance for Credit Losses, Recovery	9
Financing Receivable, Allowance for Credit Losses	1,699	1,987
Portfolio loans, net \| Residential real estate
Financing Receivable, Impaired [Line Items]
Provision for Loan, Lease, and Other Losses	(288)
Unpaid Contractual Principal Balance	409	2,425
Recorded Investment With No Allowance	408	1,659
Recorded Investment With Allowance	0	618
Total Recorded Investment	408	2,277
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0	52
Impaired Financing Receivable, Related Allowance	0	52
Average Recorded Investment	408	778
Financing Receivable, Allowance for Credit Losses, Write-downs	(67)
Financing Receivable, Allowance for Credit Losses, Recovery	364
Financing Receivable, Allowance for Credit Losses	1,625	1,616
Portfolio loans, net \| Consumer and other
Financing Receivable, Impaired [Line Items]
Provision for Loan, Lease, and Other Losses	233
Unpaid Contractual Principal Balance	0	329
Recorded Investment With No Allowance	0	0
Recorded Investment With Allowance	0	312
Total Recorded Investment	0	312
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0	26
Impaired Financing Receivable, Related Allowance	0	26
Average Recorded Investment	0	0
Financing Receivable, Allowance for Credit Losses, Write-downs	(129)
Financing Receivable, Allowance for Credit Losses, Recovery	13
Financing Receivable, Allowance for Credit Losses	$ 848	$ 731

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Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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