Allowance for Expected Credit Losses and Credit Quality - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Accrued interest	$ 65,900		$ 65,700
Accounting Standards Update 2016-13
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit losses			163,225
Accounting Standards Update 2016-13 | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit losses		$ 82,319	82,300
Consumer Portfolio Segment [Member] | Consumer - Home equity
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans Converted to Term	$ 6,600
Allowance for credit losses			$ 14,231
Consumer Portfolio Segment [Member] | Consumer - Home equity | Accounting Standards Update 2016-13 | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit losses		$ 2,808