Revenue from Contracts with Customers - Contract Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Capitalized Contract Cost [Roll Forward]
Beginning balance	$ 189,447
Impairment	(2,000)	$ (4,000)
Ending balance	175,966	189,447
Costs to Obtain Contracts
Capitalized Contract Cost [Roll Forward]
Beginning balance	21,298	19,353
Additions	9,378	7,924
Amortization	(7,081)	(6,404)
Other	0	425
Ending balance	23,595	21,298	$ 19,353
Costs to Fulfill Contracts
Capitalized Contract Cost [Roll Forward]
Beginning balance	189,448	194,501
Additions	28,588	39,168
Amortization	(39,444)	(37,904)	(40,000)
Impairment	(2,405)	(4,013)
Other	(219)	(2,304)
Ending balance	$ 175,968	$ 189,448	$ 194,501