Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Class A Common Stock, Class B Common Stock and Class C Capital Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income
Beginning Balance at Dec. 31, 2018	$ 3,267,179	$ 21	$ 3,939,842	$ (671,779)	$ (905)
Beginning Balance (in shares) at Dec. 31, 2018		203,904,265
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common and capital stock upon exercise of stock options	41,014		41,014
Issuance of common and capital stock upon exercise of stock options (in shares)		1,891,111
Vesting of restricted stock units (in shares)		1,633,962
Restricted stock units withheld for tax liability	(3)		(3)
Restricted stock units withheld for tax liability (in shares)		(92)
Share-based compensation expense	160,826		160,826
Net income (loss)	(204,151)			(204,151)
Other comprehensive income (loss)	1,689				1,689
Ending Balance at Sep. 30, 2019	3,451,878	$ 21	4,327,003	(875,930)	784
Ending Balance (in shares) at Sep. 30, 2019		207,429,246
Beginning Balance at Jun. 30, 2019	3,278,106	$ 21	4,088,470	(811,281)	896
Beginning Balance (in shares) at Jun. 30, 2019		206,513,636
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common and capital stock upon exercise of stock options	8,017		8,017
Issuance of common and capital stock upon exercise of stock options (in shares)		347,261
Vesting of restricted stock units (in shares)		568,355
Restricted stock units withheld for tax liability (in shares)		(6)
Share-based compensation expense	45,192		45,192
Premiums paid for capped call confirmations	(150,530)		(150,530)
Equity component of issuances of Notes, net of issuance costs	335,854		335,854
Net income (loss)	(64,649)			(64,649)
Other comprehensive income (loss)	(112)				(112)
Ending Balance at Sep. 30, 2019	3,451,878	$ 21	4,327,003	(875,930)	784
Ending Balance (in shares) at Sep. 30, 2019		207,429,246
Beginning Balance at Dec. 31, 2019	3,435,421	$ 21	4,412,200	(977,140)	340
Beginning Balance (in shares) at Dec. 31, 2019		209,066,855
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common and capital stock upon exercise of stock options	$ 371,228	$ 2	371,226
Issuance of common and capital stock upon exercise of stock options (in shares)	11,779,104	11,779,104
Vesting of restricted stock units (in shares)		2,191,719
Restricted stock units withheld for tax liability	$ (2)		(2)
Restricted stock units withheld for tax liability (in shares)		(32)
Share-based compensation expense	158,125		158,125
Issuance of Class C capital stock in connection with equity offering, net of issuance costs	411,523	$ 1	411,522
Issuance of Class C capital stock in connection with equity offering, net of issuance costs (in shares)		8,800,000
Equity component of issuances of Notes, net of issuance costs	154,813		154,813
Partial repurchase of 2021 Notes	(21,784)		(21,784)
Partial repurchase of Notes (in shares)		753,936
Partial unwind of capped call transactions (in shares)		(317,865)
Partial conversion of 2020 Notes	2,061		2,061
Partial conversion of 2020 Notes (in shares)		85,106
Net income (loss)	(208,151)			(208,151)
Other comprehensive income (loss)	121				121
Ending Balance at Sep. 30, 2020	4,303,355	$ 24	5,488,161	(1,185,291)	461
Ending Balance (in shares) at Sep. 30, 2020		232,358,823
Beginning Balance at Jun. 30, 2020	4,023,058	$ 23	5,246,371	(1,224,861)	1,525
Beginning Balance (in shares) at Jun. 30, 2020		226,041,936
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common and capital stock upon exercise of stock options	186,243	$ 1	186,242
Issuance of common and capital stock upon exercise of stock options (in shares)		5,454,246
Vesting of restricted stock units (in shares)		777,561
Restricted stock units withheld for tax liability	(2)		(2)
Restricted stock units withheld for tax liability (in shares)		(26)
Share-based compensation expense	53,489		53,489
Partial conversion of 2020 Notes	2,061		2,061
Partial conversion of 2020 Notes (in shares)		85,106
Net income (loss)	39,570			39,570
Other comprehensive income (loss)	(1,064)				(1,064)
Ending Balance at Sep. 30, 2020	$ 4,303,355	$ 24	$ 5,488,161	$ (1,185,291)	$ 461
Ending Balance (in shares) at Sep. 30, 2020		232,358,823