Income Taxes, Textuals (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Valuation allowance for deferred tax assets	$ (251)	$ (251)	$ (251)
Tax Credit Carryforward, Expiration Being Date	begin expiring in 2035
Bad debt from acquired savings banks	$ 100,000
Deferred tax on bad debt from acquired savings banks	25,000
Unrecognized tax benefit impact on effective tax rate	3,000	$ 2,000
Loss on prepayments of FHLB advances	44,650
Risk Management and Shared Serivies [Member]
Operating Loss Carryforwards [Line Items]
Loss on prepayments of FHLB advances	45,000
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	92,000
Operating tax loss carryforwards from acquisitions	$ 40,000
Operating Loss Carryforwards, Expiration Begin Date	begin expiring in 2031
Tax Credit Carryforward, Amount	$ 2,000
Internal Revenue Service (IRS)
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 3,000