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Allowance for Credit Losses - Summary of Allowance for Credit Losses and Recorded Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment			$ 2,200
Allowance for Loan Losses, Collectively Evaluated for Impairment			60,024
Total	$ 117,612	$ 62,224	62,224	$ 60,996
Portfolio Loans, Individually Evaluated for Impairment			75,337
Portfolio Loans, Collectively Evaluated for Impairment			7,061,815
Total	7,225,860		7,137,152
Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	5,977,643		5,756,971
Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	$ 1,248,217		1,380,181
Commercial real estate \| Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment			2,023
Allowance for Loan Losses, Collectively Evaluated for Impairment			28,554
Total			30,577
Portfolio Loans, Individually Evaluated for Impairment			47,920
Portfolio Loans, Collectively Evaluated for Impairment			3,368,598
Total			3,416,518
Commercial and industrial \| Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment			55
Allowance for Loan Losses, Collectively Evaluated for Impairment			15,626
Total			15,681
Portfolio Loans, Individually Evaluated for Impairment			17,606
Portfolio Loans, Collectively Evaluated for Impairment			1,703,227
Total			1,720,833
Commercial construction \| Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment			113
Allowance for Loan Losses, Collectively Evaluated for Impairment			7,787
Total			7,900
Portfolio Loans, Individually Evaluated for Impairment			1,914
Portfolio Loans, Collectively Evaluated for Impairment			373,531
Total			375,445
Consumer real estate \| Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment			0
Allowance for Loan Losses, Collectively Evaluated for Impairment			6,337
Total			6,337
Portfolio Loans, Individually Evaluated for Impairment			7,884
Portfolio Loans, Collectively Evaluated for Impairment			1,537,439
Total			1,545,323
Other consumer \| Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment			9
Allowance for Loan Losses, Collectively Evaluated for Impairment			1,720
Total			1,729
Portfolio Loans, Individually Evaluated for Impairment			13
Portfolio Loans, Collectively Evaluated for Impairment			79,020
Total			$ 79,033