Allowance for Credit Losses - Loans on Nonaccrual Status and Loans Past Due 90 Days or More and Still Accruing (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($)		Jun. 30, 2020 USD ($)
Financing Receivable, Nonaccrual [Line Items]
Beginning of Period Nonaccrual			$ 54,057
End of Period Nonaccrual	$ 90,113	[1]	90,113	[1]
Nonaccrual With No Related Allowance	19,507		19,507
Past Due 90+ Days Still Accruing	2,200		2,200
Interest Income Recognized on Nonaccrual(1)	145	[2]	312	[2]
Commercial | Commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Beginning of Period Nonaccrual			25,356
End of Period Nonaccrual	55,776	[1]	55,776	[1]
Nonaccrual With No Related Allowance	14,889		14,889
Past Due 90+ Days Still Accruing	0		0
Interest Income Recognized on Nonaccrual(1)	3	[2]	12	[2]
Commercial | Commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Beginning of Period Nonaccrual			10,911
End of Period Nonaccrual	2,626	[1]	2,626	[1]
Nonaccrual With No Related Allowance	0		0
Past Due 90+ Days Still Accruing	1,506		1,506
Interest Income Recognized on Nonaccrual(1)	9	[2]	23	[2]
Commercial | Commercial construction
Financing Receivable, Nonaccrual [Line Items]
Beginning of Period Nonaccrual			737
End of Period Nonaccrual	1,504	[1]	1,504	[1]
Nonaccrual With No Related Allowance	1,218		1,218
Past Due 90+ Days Still Accruing	0		0
Interest Income Recognized on Nonaccrual(1)	0	[2]	0	[2]
Commercial | Business banking
Financing Receivable, Nonaccrual [Line Items]
Beginning of Period Nonaccrual			9,863
End of Period Nonaccrual	16,475	[1]	16,475	[1]
Nonaccrual With No Related Allowance	3,002		3,002
Past Due 90+ Days Still Accruing	0		0
Interest Income Recognized on Nonaccrual(1)	57	[2]	104	[2]
Consumer | Consumer real estate
Financing Receivable, Nonaccrual [Line Items]
Beginning of Period Nonaccrual			6,063
End of Period Nonaccrual	11,873	[1]	11,873	[1]
Nonaccrual With No Related Allowance	398		398
Past Due 90+ Days Still Accruing	572		572
Interest Income Recognized on Nonaccrual(1)	75	[2]	170	[2]
Consumer | Other consumer
Financing Receivable, Nonaccrual [Line Items]
Beginning of Period Nonaccrual			1,127
End of Period Nonaccrual	1,859	[1]	1,859	[1]
Nonaccrual With No Related Allowance	0		0
Past Due 90+ Days Still Accruing	122		122
Interest Income Recognized on Nonaccrual(1)	$ 1	[2]	$ 3	[2]

[1] We had 2,360 loans that were modified totaling $1.4 billion under the CARES Act at June 30, 2020. These customers were not considered past due as a result of their delayed payments. Upon exiting the loan modification deferral program, the measurement of loan delinquency will resume where it left off upon entry into the program. Due to the modification program, this delinquency table may not accurately reflect the credit risk associated with these loans.

[2] Represents only cash payments received and applied to interest on nonaccrual loans.