Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Contingency [Line Items]
Tax Cuts and Jobs Act of 2017, income tax benefit	$ 9,800
Tax Cuts and Jobs Act of 2017, measurement period adjustment, income tax benefit	3,900
Tax Cuts and Jobs Act of 2017, measurement period adjustment, adjustment to prior year tax return	5,900
Tax Cuts and Jobs Act of 2017, provisional income tax expense		$ 47,200
Deferred tax assets expected to be realized	141,100
Valuation allowance	0	3,431
Deferred tax assets, not subject to expiration	88,000
Tax credit carryforward, amount	3,400	6,200
Unrecognized tax benefits, income tax penalties and interest accrued	227	105	$ 38
Unrecognized tax benefits that would impact effective tax rate	15,200	12,300	$ 9,900
Unrecognized tax benefits, income tax penalties and interest accrued that would impact effective tax rate	193	$ 76
Approximate range of uncertain income tax positions expected to be settled or resolved during the next 12 months, minimum	316
Period through 2035
Income Tax Contingency [Line Items]
Deferred tax assets, subject to expiration	33,000
Federal and State | Period through 2027
Income Tax Contingency [Line Items]
Tax credit carryforward, amount	$ 20,100