Commitment and Contingencies - 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
Commitments and Contingencies Disclosure [Abstract]
Rent expense	$ 3,100	$ 1,700	$ 8,500	$ 5,000
Restricted cash related to irrevocable standby letters of credit	6,700		6,700
Cost and expenses related to bandwidth and other co-location commitments	9,700	$ 6,800	26,800	$ 19,500
Build-to-suit lease financing obligation	$ 10,501		$ 10,501		$ 10,443