Loans - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructurings loans	$ 194,700	$ 206,300
Allowance for loan losses	$ 444,490	200,307	$ 184,911	$ 180,424
Loans to Mortgage Companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of loans collateralized with government guaranteed loans	90.00%
Allowance For TDRs To Recorded Investment Of TDRs
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	$ 13,900	$ 19,700
Ratio of the allowance for loan losses to loans	7.00%	10.00%
Loans Held For Sale, Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructurings loans	$ 50,500	$ 51,100
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance - purchased credit-impaired loans		848
Allowance for loan losses		158,598
Consumer | Consumer Real Estate (a)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Modified interest rate increase	1.00%
TDRS Maturities	40 years
Allowance for loan losses	$ 123,022	28,443	34,154	37,439
Consumer | Credit Card and Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	$ 19,327	13,266	12,662	$ 12,727
Consumer | Permanent Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
TDR, reduction of interest rate by increment, basis points	0.25%
Minimum | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forbearance agreements time period	6 months
Minimum | Consumer | Consumer Real Estate (a)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Modified interest rate	2.00%
Modified interest rate time period	5 years
Maximum | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forbearance agreements time period	12 months
Maximum | Consumer | Consumer Real Estate (a)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Modified interest rate time period	5 years
TRUPS
Accounts, Notes, Loans and Financing Receivable [Line Items]
Small Bank And Business Loan, Total Asset Maximum Cap	$ 15,000,000
Heloc And Real Estate Installment Classes | Consumer | Consumer Real Estate (a)
Accounts, Notes, Loans and Financing Receivable [Line Items]
TDR, reduction of interest rate by increment, basis points	0.25%
Modified interest rate increase	2.00%
Heloc And Real Estate Installment Classes | Minimum | Consumer | Consumer Real Estate (a)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Modified interest rate	1.00%
Modified interest rate time period	5 years
Heloc And Real Estate Installment Classes | Maximum | Consumer | Consumer Real Estate (a)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Modified interest rate time period	5 years
Credit Card | Consumer | Credit Card and Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit card workout program, granted rate reduction	0.00%
Credit Card | Minimum | Consumer | Credit Card and Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Payment reductions, time period	6 months
Credit Card | Maximum | Consumer | Credit Card and Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Payment reductions, time period	1 year
Credit card workout program, term extension	5 years
Purchased credit-impaired loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance - purchased credit-impaired loans		2,000
Allowance for loan losses			3,413
Allowance for Loan and Lease Losses Write-offs, Net		5,800
Provision for Loan, Lease, and Other Losses		$ 1,300
Purchased credit-impaired loans | Consumer | Consumer Real Estate (a)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses			1,123
Purchased credit-impaired loans | Consumer | Credit Card and Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses			$ 149