Net Income per Share - Schedule of Shares Excluded from Computation of Diluted EPS (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	28,235	19,752
Service-based RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	2,565	2,815
Performance-based RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	1,484	1,529
Convertible senior notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	12,093	7,704
Warrants related to issuance of convertible senior notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	12,093	7,704