Segment Information - Segment Reconciliation of Operating Income to Net Income (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Total Segment EBITDA	$ 104,933,000	$ 112,779,000
Interest expense	(15,672,000)	(19,930,000)
Depreciation and amortization	(19,718,000)	(37,823,000)
Other components of net periodic pension cost	453,000	(201,000)
Loss on early extinguishment of debt	(299,000)	0
Impairment charges	0	(98,000)
Restructuring and integration expenses	(9,234,000)	(9,845,000)
Transaction costs	(10,546,000)	(6,534,000)
Stock-based compensation expense (benefit)	(1,971,000)	6,064,000
Non-cash loss from remeasurement of indemnification asset	0	(3,801,000)
Other	369,000	900,000
Income before (provision) for income taxes	48,315,000	41,511,000
Severance costs	600,000	3,300,000
COVID-19 Terminations
Segment Reporting Information [Line Items]
Severance costs	$ 0	$ 1,000,000.0