Business Segment Information - Reconciliation of Segment Profit to Income Before Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Reconciliation of segment profit to income before income taxes
Income from continuing operations before income taxes	$ 10,780	$ 12,950	$ 15,472	$ 1,550
Stock compensation expense	6,592	5,207	12,389	14,607
Depreciation and amortization	23,888	28,191	47,246	53,608
Interest expense	7,995	9,070	16,953	18,107
Interest and other income	(551)	(1,821)	(1,770)	(3,580)
Special charges	8,309		8,309
Segment Profit (Loss)	$ 57,013	$ 53,597	$ 98,599	$ 84,292