Other Assets - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Other Assets
Costs to obtain contracts	$ 219,307	$ 157,970
Accumulated amortization of costs to obtain contracts	(24,992)	(16,485)
Unbilled receivables	81,703	51,710
Operating lease right-of-use assets	20,257	25,465
Other assets	39,410	27,804
Total	335,685	246,464
Amortization cost	$ 8,600	$ 6,500