Business Segment Information - Reconciliation of Segment Profit to Income Before Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Reconciliation of segment profit to income before income taxes
Income (loss) from continuing operations before income taxes	$ (19,626)	$ 4,903	$ (4,154)	$ 6,453
Stock compensation expense	5,442	4,604	17,831	19,211
Depreciation and amortization	24,730	28,890	71,976	82,498
Interest expense	7,286	8,935	24,239	27,042
Interest and other income	(349)	(1,699)	(2,119)	(5,279)
Special charges	16,599		24,908
Segment Profit (Loss)	$ 34,082	$ 45,633	$ 132,681	$ 129,925