Overview and Basis of Presentation - Schedule of Cumulative Effects of New Revenue Standard on Cash Flows Statement (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities
Net loss	$ (29,325)	$ (25,081)	[1],[2],[3]
Adjustments to reconcile net loss to net cash provided by operating activities
Share-based compensation	26,988	19,104	[3]
Amortization of deferred costs	4,510	3,179	[3]
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(3,364)	(380)	[3]
Deferred costs	(7,043)	(4,102)	[3]
Deferred revenue	10,910	6,704	[3]
Net cash provided by operating activities	16,242	7,282	[3]
Net increase in cash, cash equivalents and restricted cash	499,657	15,714	[3]
Cash, cash equivalents and restricted cash at beginning of period	110,888	95,062	[3]
Cash, cash equivalents and restricted cash at end of period	$ 610,545	110,776	[3]
As Previously Reported
Cash flows from operating activities
Net loss		(26,994)
Adjustments to reconcile net loss to net cash provided by operating activities
Share-based compensation		19,213
Amortization of deferred costs		0
Changes in operating assets and liabilities:
Prepaid expenses and other current assets		(513)
Deferred costs		0
Deferred revenue		7,585
Net cash provided by operating activities		7,149
Net increase in cash, cash equivalents and restricted cash		15,581
Cash, cash equivalents and restricted cash at beginning of period		93,677
Cash, cash equivalents and restricted cash at end of period		109,258
Accounting Standards Update 2014-09 | Adjustments
Cash flows from operating activities
Net loss		1,913
Adjustments to reconcile net loss to net cash provided by operating activities
Share-based compensation		(109)
Amortization of deferred costs		3,179
Changes in operating assets and liabilities:
Prepaid expenses and other current assets		133
Deferred costs		(4,102)
Deferred revenue		(881)
Net cash provided by operating activities		133
Net increase in cash, cash equivalents and restricted cash		133
Cash, cash equivalents and restricted cash at beginning of period		1,385
Cash, cash equivalents and restricted cash at end of period		$ 1,518

[1] See Note 1 for a summary of adjustments.

[2] See Note 1 for a summary of adjustments.

[3] See Note 1 for a summary of adjustments.