Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Effective income tax rate	30.00%	18.00%
Valuation allowances against deferred tax assets	$ 9,400		$ 7,200
Net deferred tax liability	27,600		33,300
Income tax expense	(1,363)	$ (1,470)
Adoption adjustment	297,331	276,609	328,713	$ 285,696
Reduction to income taxes payable and deferred tax assets		1,300
Error Adjustment [Member]
Income tax expense	1,800
Correction In Calculation Of Valuation Allowance And Uncertain Tax Position [Member]
Increase in valuation allowance	1,800
Accounting Standards Update 2020-06 [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Adoption adjustment	(19,639)
Retained Earnings [Member]
Adoption adjustment	13,671	30,039	20,022	36,704
Retained Earnings [Member] | Accounting Standards Update 2020-06 [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Adoption adjustment	(3,213)		3,200
Additional Paid-In Capital [Member]
Adoption adjustment	301,449	$ 273,821	316,192	$ 271,782
Additional Paid-In Capital [Member] | Accounting Standards Update 2020-06 [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Adoption adjustment	$ (16,426)		$ 16,400