Allowance for Credit Losses - Loans on Nonaccrual Status and Loans Past Due 90 Days or More and Still Accruing (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Financing Receivable, Nonaccrual [Line Items]
Beginning of Period Nonaccrual	$ 54,057
End of Period Nonaccrual	146,774
Nonaccrual With No Related Allowance	71,410
Past Due 90+ Days Still Accruing	503
Interest Income Recognized on Nonaccrual	826
Commercial | Commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Beginning of Period Nonaccrual	25,356
End of Period Nonaccrual	101,070
Nonaccrual With No Related Allowance	60,401
Past Due 90+ Days Still Accruing	0
Interest Income Recognized on Nonaccrual	22
Commercial | Commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Beginning of Period Nonaccrual	10,911
End of Period Nonaccrual	16,985
Nonaccrual With No Related Allowance	6,436
Past Due 90+ Days Still Accruing	0
Interest Income Recognized on Nonaccrual	101
Commercial | Other Consumer
Financing Receivable, Nonaccrual [Line Items]
Beginning of Period Nonaccrual	737
End of Period Nonaccrual	384
Nonaccrual With No Related Allowance	285
Past Due 90+ Days Still Accruing	0
Interest Income Recognized on Nonaccrual	0
Commercial | Business banking
Financing Receivable, Nonaccrual [Line Items]
Beginning of Period Nonaccrual	9,863
End of Period Nonaccrual	17,122
Nonaccrual With No Related Allowance	3,890
Past Due 90+ Days Still Accruing	371
Interest Income Recognized on Nonaccrual	275
Consumer | Consumer real estate
Financing Receivable, Nonaccrual [Line Items]
Beginning of Period Nonaccrual	6,063
End of Period Nonaccrual	11,117
Nonaccrual With No Related Allowance	398
Past Due 90+ Days Still Accruing	132
Interest Income Recognized on Nonaccrual	423
Consumer | Other consumer
Financing Receivable, Nonaccrual [Line Items]
Beginning of Period Nonaccrual	1,127
End of Period Nonaccrual	96
Nonaccrual With No Related Allowance	0
Past Due 90+ Days Still Accruing	0
Interest Income Recognized on Nonaccrual	$ 4