Allowance for Credit Losses and Credit Quality Information - Schedule of Residential and Consumer Credit Exposure (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans		$ 8,464,562	$ 4,894,257
Total		100.00%
Accrued troubled debt restructured loans		$ 14,000
Reverse mortgage, fair value	$ 10,100	16,600	16,500
Acquired nonimpaired loans		3,221,316	$ 429,982
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans		999,879
Consumer(3)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans		1,128,731
Total Residential and Consumer Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans		$ 2,128,610
Total		100.00%
Acquired nonimpaired loans		$ 1,100,000
Acquired impaired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total		0.00%
Acquired impaired | Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans		$ 7,326
Acquired impaired | Consumer(3)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans		2,127
Acquired impaired | Total Residential and Consumer Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans		$ 9,453
Total		0.00%
Nonperforming | Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans		$ 12,858
Nonperforming | Consumer(3)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans		7,374
Nonperforming | Total Residential and Consumer Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans		$ 20,232
Total		1.00%
Performing | Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans		$ 979,695
Performing | Consumer(3)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans		1,119,230
Performing | Total Residential and Consumer Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans		$ 2,098,925
Total		99.00%