Stockholders' Equity - Weighted Average Assumptions Used for the Fair Value of the Option Component of the Purchase Plan Shares Estimated at Grant Date Using Black-Scholes Option Pricing Model (Detail) - Employee Stock Purchase Plan - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	1 year 1 month 6 days	1 year	1 year 4 months 24 days
Expected volatility	52.70%	55.00%	50.00%
Risk-free interest rate	0.10%	0.90%	2.20%
Expected dividends	0.00%	0.00%	0.00%
Weighted average fair value at grant date (usd per share)	$ 246.84	$ 96.94	$ 86.02