Loans and Allowance for Credit Losses - Summary of Impaired Loans (Details) - USD ($) $ in Thousands		Mar. 31, 2019	Dec. 31, 2018
Accounts Notes And Loans Receivable [Line Items]
Recorded Investment in Impaired Loans, With no related allowance for credit losses	[1]		$ 22,251
Unpaid Principal Balance, With no related allowance for credit losses			35,443
Nonaccrual Loans Included in Impaired Loans, with no related allowance for credit losses			20,713
Undisbursed Commitments, With no related allowance for credit losses			3,658
Recorded Investment in Impaired Loans, With allowance for credit losses recorded	[1]	$ 80,873	56,953
Unpaid Principal Balance, With allowance for credit losses recorded		97,105	58,374
Related Specific Allowance, With allowance for credit losses recorded		14,585	7,432
Nonaccrual Loans Included in Impaired Loans, With allowance for credit losses recorded		74,865	50,870
Undisbursed Commitments, With allowance for credit losses recorded		8,339	3,269
Commercial and Industrial
Accounts Notes And Loans Receivable [Line Items]
Recorded Investment in Impaired Loans, With no related allowance for credit losses	[1]	9,063	20,713
Unpaid Principal Balance, With no related allowance for credit losses		8,997	33,908
Nonaccrual Loans Included in Impaired Loans, with no related allowance for credit losses			20,713
Undisbursed Commitments, With no related allowance for credit losses		1,333	3,658
Recorded Investment in Impaired Loans, With allowance for credit losses recorded	[1]	80,168	56,223
Unpaid Principal Balance, With allowance for credit losses recorded		95,616	56,871
Related Specific Allowance, With allowance for credit losses recorded		14,531	7,300
Nonaccrual Loans Included in Impaired Loans, With allowance for credit losses recorded		74,657	50,641
Undisbursed Commitments, With allowance for credit losses recorded		8,329	3,259
Commercial and Industrial | Energy Sector
Accounts Notes And Loans Receivable [Line Items]
Recorded Investment in Impaired Loans, With no related allowance for credit losses	[1]		20,713
Unpaid Principal Balance, With no related allowance for credit losses			33,908
Nonaccrual Loans Included in Impaired Loans, with no related allowance for credit losses			20,713
Undisbursed Commitments, With no related allowance for credit losses			3,658
Recorded Investment in Impaired Loans, With allowance for credit losses recorded	[1]	13,880
Unpaid Principal Balance, With allowance for credit losses recorded		27,915
Related Specific Allowance, With allowance for credit losses recorded		1,571
Nonaccrual Loans Included in Impaired Loans, With allowance for credit losses recorded		13,880
Undisbursed Commitments, With allowance for credit losses recorded		2,964
Commercial and Industrial | General C&I
Accounts Notes And Loans Receivable [Line Items]
Recorded Investment in Impaired Loans, With no related allowance for credit losses	[1]	9,063
Unpaid Principal Balance, With no related allowance for credit losses		8,997
Undisbursed Commitments, With no related allowance for credit losses		1,333
Recorded Investment in Impaired Loans, With allowance for credit losses recorded	[1]	38,968	28,684
Unpaid Principal Balance, With allowance for credit losses recorded		39,420	28,677
Related Specific Allowance, With allowance for credit losses recorded		8,365	3,559
Nonaccrual Loans Included in Impaired Loans, With allowance for credit losses recorded		34,459	24,103
Undisbursed Commitments, With allowance for credit losses recorded		3,161	930
Commercial and Industrial | Healthcare
Accounts Notes And Loans Receivable [Line Items]
Recorded Investment in Impaired Loans, With allowance for credit losses recorded	[1]	4,449	4,496
Unpaid Principal Balance, With allowance for credit losses recorded		4,496	4,496
Related Specific Allowance, With allowance for credit losses recorded		209	256
Nonaccrual Loans Included in Impaired Loans, With allowance for credit losses recorded		4,449	4,496
Commercial and Industrial | Restaurant Industry
Accounts Notes And Loans Receivable [Line Items]
Recorded Investment in Impaired Loans, With allowance for credit losses recorded	[1]	22,871	23,043
Unpaid Principal Balance, With allowance for credit losses recorded		23,785	23,698
Related Specific Allowance, With allowance for credit losses recorded		4,386	3,485
Nonaccrual Loans Included in Impaired Loans, With allowance for credit losses recorded		21,869	22,042
Undisbursed Commitments, With allowance for credit losses recorded		2,204	2,329
Consumer
Accounts Notes And Loans Receivable [Line Items]
Recorded Investment in Impaired Loans, With no related allowance for credit losses	[1]	10,594	1,538
Unpaid Principal Balance, With no related allowance for credit losses		10,521	1,535
Undisbursed Commitments, With no related allowance for credit losses		1,333
Recorded Investment in Impaired Loans, With allowance for credit losses recorded	[1]	257	254
Unpaid Principal Balance, With allowance for credit losses recorded		254	254
Related Specific Allowance, With allowance for credit losses recorded		13	25
Consumer | Residential Real Estate
Accounts Notes And Loans Receivable [Line Items]
Recorded Investment in Impaired Loans, With no related allowance for credit losses	[1]	1,531	1,538
Unpaid Principal Balance, With no related allowance for credit losses		1,524	1,535
Consumer | Other
Accounts Notes And Loans Receivable [Line Items]
Recorded Investment in Impaired Loans, With allowance for credit losses recorded	[1]	257
Unpaid Principal Balance, With allowance for credit losses recorded		254
Related Specific Allowance, With allowance for credit losses recorded		13
Small Business Lending
Accounts Notes And Loans Receivable [Line Items]
Recorded Investment in Impaired Loans, With allowance for credit losses recorded	[1]	448	476
Unpaid Principal Balance, With allowance for credit losses recorded		1,235	1,249
Related Specific Allowance, With allowance for credit losses recorded		41	107
Nonaccrual Loans Included in Impaired Loans, With allowance for credit losses recorded		208	229
Undisbursed Commitments, With allowance for credit losses recorded		$ 10	$ 10

[1] The recorded investment of a loan also includes any interest receivable, net unearned discount or fees, and unamortized premium or discount.