Quarterly Information (Unaudited) (Narrative) (Details) - USD ($)	3 Months Ended							12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information [Line Items]
Loss on extinguishment of debt		$ 5,600,000						$ 5,569,000	$ 0	$ 0
Intangible asset, pre-tax impairment charge									3,300,000	0
Stock-based compensation, net excess tax benefits	$ 600,000		$ (100,000)	$ 1,600,000			$ 2,300,000	$ 500,000	3,900,000	$ 1,600,000
Income tax effects from changes in tax rates	$ 2,500,000			(5,900,000)	$ (500,000)	$ (1,400,000)
Pre-Qualifications [Member]
Quarterly Financial Information [Line Items]
Intangible asset, pre-tax impairment charge				$ 3,300,000					$ 3,300,000