Discontinued Operations - Income (Loss) From Discontinued Operations (Details) - Discontinued Operations, Held-for-sale - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues [Abstract]
Total revenue	$ 442,373	$ 443,389	$ 450,458
Operating expenses
Selling, general and administrative	34,011	39,128	43,563
Depreciation and amortization	62,930	111,467	122,014
Total operating expenses	253,977	344,225	354,242
Operating income	188,396	99,164	96,216
Other income:
Interest expense	(20,455)	(29,286)	(34,838)
Income before income taxes	167,941	69,878	61,378
Income tax expense	43,844	16,310	16,860
Income from discontinued operations, net of tax	124,097	53,568	44,518
Service revenue and other
Revenues [Abstract]
Total revenue	401,035	375,730	382,948
Equipment revenue
Revenues [Abstract]
Total revenue	41,338	67,659	67,510
Cost of services
Operating expenses
Cost of services and cost of goods sold	116,394	128,482	125,082
Cost of goods sold
Operating expenses
Cost of services and cost of goods sold	$ 40,642	$ 65,148	$ 63,583