Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Net tax credits	$ 1,100	$ 4,800	$ 1,200
Tax Cuts and Jobs Act, Measurement Period Adjustment, Income Tax Expense (Benefit)			10,400
Increase (decrease) in deferred income taxes	19,300
Deferred tax expense (benefit)	(31,236)	927	9,472
Tax benefit directly allocated to shareholder's equity	27,800
Deferred tax assets	238,703	203,640
Valuation allowance	37,374	38,181
Valuation allowance increase (decrease)	(800)
Unrecognized deferred tax liability for thrift bad-debt reserves	15,300
Unrecognized tax benefits that would impact effective tax rate	3,500	3,900	2,300
Cumulative taxable temporary differences	58,000
Interest and penalties	100	100	$ 0
Accrued interest and penalties related to UTBs	1,700	1,800
Cumulative Effect, Period of Adoption, Adjustment [Member]
Operating Loss Carryforwards [Line Items]
Deferred tax assets		15,900
Research Tax Credit Carryforward [Member]
Operating Loss Carryforwards [Line Items]
Net tax credits		3,000
Investment Tax Credit Carryforward [Member]
Operating Loss Carryforwards [Line Items]
Net tax credits	800	2,400
General Business Tax Credit Carryforward [Member]
Operating Loss Carryforwards [Line Items]
Net tax credits	300
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowance	37,400	$ 38,200
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	630,800
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Domestic	1,100,000
Minimum [Member]
Operating Loss Carryforwards [Line Items]
Decrease in Unrecognized Tax Benefits is Reasonably Possible	1,600
Maximum [Member]
Operating Loss Carryforwards [Line Items]
Decrease in Unrecognized Tax Benefits is Reasonably Possible	$ 2,700