Share-Based Awards - Summary of Option Award and Stock Appreciation Rights Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Number of Shares Subject to Existing Options
Number of Shares Subject to Existing Option Awards and Stock Appreciation Rights, Beginning Balance (in shares)	26,645,206
Number of Shares Subject to Existing Option Awards and Stock Appreciation Rights, Granted (in shares)	6,963,320
Number of Shares Subject to Existing Option Awards and Stock Appreciation Rights, Exercised (in shares)	(5,472,728)
Number of Shares Subject to Existing Option Awards and Stock Appreciation Rights, Forfeited or cancelled (in shares)	(825,688)
Number of Shares Subject to Existing Option Awards and Stock Appreciation Rights, Ending Balance (in shares)		26,645,206
Number of Shares Subject to Existing Option Awards and Stock Appreciation Rights, Vested and exercisable, Ending balance (in shares)	15,287,932
Weighted- Average Exercise Price Per Share
Weighted-Average Exercise Price Per Share, Beginning Balance (usd per share)	$ 27.70
Weighted-Average Exercise Price Per Share, Granted (usd per share)	48.95
Weighted-Average Exercise Price Per Share, Exercised (usd per share)	21.94
Weighted-Average Exercise Price Per Share, Forfeited or cancelled (usd per share)	35.32
Weighted-Average Exercise Price Per Share, Ending Balance (usd per share)	34.04	$ 27.70
Weighted-Average Exercise Price Per Share, Vested and exercisable (usd per share)	$ 29.73
Weighted- Average Remaining Contractual Life (Years)
Weighted-Average Remaining Contractual Life (Years)	6 years 2 months 23 days	5 years 8 months 19 days
Weighted-Average Remaining Contractual Life (Years), Vested and exercisable	4 years 8 months 19 days
Aggregate Intrinsic Value (in thousands)
Aggregate Intrinsic Value	$ 97,941	$ 355,739
Aggregate Intrinsic Value Vested, and exercisable	$ 75,867