Revenues - Performance Obligations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Accounts receivable, net	$ 95,305		$ 106,812
Unearned income	18,138		20,668
Unearned income - long term	32,037		$ 28,437
Revenue recognized that was included in unearned income	5,200	$ 6,100
Transaction price allocated to performance obligations that are unsatisfied or partially satisfied	$ 288,700
Professional Services, All Other Contracts | Minimum | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, period of expected timing of satisfaction	2 years
Professional Services, All Other Contracts | Maximum | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, period of expected timing of satisfaction	5 years