Fair Value Measurement - Marketable Security Contractual Maturities (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mature within one year		$ 97,438
Mature after one year through two years		146,197
Mature over two years		153,802
Fair Value		397,458
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mature within one year	$ 101,879	92,559
Mature after one year through two years	120,990	134,199
Mature over two years	31,516	46,556
Fair Value	254,385	273,314
Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mature within one year	0	0
Mature after one year through two years	4,948	2,000
Mature over two years	85,268	94,704
Fair Value	90,216	96,704
U.S. government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mature within one year	0	0
Mature after one year through two years	7,814	7,995
Mature over two years	11,642	12,176
Fair Value	19,456	20,171
Foreign government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mature within one year	2,856	2,877
Mature after one year through two years	0	0
Mature over two years	377	366
Fair Value	3,233	3,243
Municipal/provincial bonds and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mature within one year	0	2,002
Mature after one year through two years	1,999	2,003
Mature over two years	0	0
Fair Value	1,999	4,005
Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mature within one year	104,735	97,438
Mature after one year through two years	135,751	146,197
Mature over two years	128,803	153,802
Fair Value	$ 369,289	397,437
Pending purchases and sales
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mature within one year		0
Mature after one year through two years		0
Mature over two years		0
Fair Value		$ 21