Business Segment Information - Reconciliation of Segment Profit to Income Before Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Reconciliation of segment profit to income before income taxes
Income (loss) from continuing operations before income taxes	$ 39,414	$ 4,692
Stock compensation expense	7,057	5,797
Depreciation and amortization	21,417	23,358
Interest expense	6,426	8,958
Interest and other income	(341)	(1,219)
Special charges	1,151
Segment Profit (Loss)	$ 75,124	$ 41,586