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
	Mar. 31, 2020 USD ($)
Financing Receivable, Nonaccrual [Line Items]
Beginning of Period Nonaccrual	$ 54,057
End of Period Nonaccrual	73,799
Nonaccrual With No Related Allowance	46,554
Past Due 90 Days Still Accruing	5,294
Interest Income Recognized on Nonaccrual	881
Commercial | Commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Beginning of Period Nonaccrual	25,356
End of Period Nonaccrual	46,533
Nonaccrual With No Related Allowance	39,454
Past Due 90 Days Still Accruing	700
Interest Income Recognized on Nonaccrual	684
Commercial | Commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Beginning of Period Nonaccrual	10,911
End of Period Nonaccrual	4,505
Nonaccrual With No Related Allowance	4,054
Past Due 90 Days Still Accruing	2,615
Interest Income Recognized on Nonaccrual	64
Commercial | Commercial construction
Financing Receivable, Nonaccrual [Line Items]
Beginning of Period Nonaccrual	737
End of Period Nonaccrual	571
Nonaccrual With No Related Allowance	285
Past Due 90 Days Still Accruing	933
Interest Income Recognized on Nonaccrual	0
Commercial | Business banking
Financing Receivable, Nonaccrual [Line Items]
Beginning of Period Nonaccrual	9,863
End of Period Nonaccrual	11,316
Nonaccrual With No Related Allowance	2,363
Past Due 90 Days Still Accruing	768
Interest Income Recognized on Nonaccrual	58
Consumer | Consumer real estate
Financing Receivable, Nonaccrual [Line Items]
Beginning of Period Nonaccrual	6,063
End of Period Nonaccrual	10,616
Nonaccrual With No Related Allowance	398
Past Due 90 Days Still Accruing	83
Interest Income Recognized on Nonaccrual	47
Consumer | Other consumer
Financing Receivable, Nonaccrual [Line Items]
Beginning of Period Nonaccrual	1,127
End of Period Nonaccrual	258
Nonaccrual With No Related Allowance	0
Past Due 90 Days Still Accruing	195
Interest Income Recognized on Nonaccrual	$ 28