Revenue - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue adjustment	$ 38,614	$ 35,692	$ 99,883	$ 98,167
Contract assets	1,600		1,600		$ 700
Accounts receivable	20,909		20,909		19,327
Contract with customer, impairment losses on receivables	$ 1,000	400	$ 3,700	2,200
Capitalized contract cost, amortization period	3 years		3 years
Capitalized contract cost, amortization on previously capitalized costs	$ 300	$ 400	$ 1,100	1,200
Contract liabilities	33,100		33,100		37,630
Contract with customer, revenue recognized			29,500	$ 27,100
IGO
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable	6,000		$ 6,000		$ 7,800
Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue adjustment	$ 3,900