Stock-Based Compensation - Summary of Stock Option Activity (Detail) - Stock Options shares in Thousands	3 Months Ended
	Mar. 31, 2020 $ / shares shares
Shares Under Option
Outstanding at the beginning of the period (in shares) | shares	4,064
Granted (in shares) | shares	46
Exercised (in shares) | shares	(539)
Cancelled (in shares) | shares	(34)
Outstanding at the end of the period (in shares) | shares	3,537
Exercisable as of March 31, 2020 | shares	1,624
Weighted-Average Exercise Price
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 70.74
Granted (in dollars per share) | $ / shares	269.45
Exercised (in dollars per share) | $ / shares	35.91
Cancelled (in dollars per share) | $ / shares	139.02
Outstanding at the end of the period (in dollars per share) | $ / shares	77.97
Exercisable as of March 31, 2020 | $ / shares	$ 40.82