Fair Value Measurement - Marketable Security Contractual Maturities (Detail) - USD ($) $ in Thousands	Jun. 30, 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	$ 100,989	92,559
Mature after one year through two years	101,991	134,199
Mature over two years	16,592	46,556
Fair Value	219,572	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	5,117	2,000
Mature over two years	78,892	94,704
Fair Value	84,009	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	7,745	7,995
Mature over two years	11,201	12,176
Fair Value	18,946	20,171
Foreign government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mature within one year	2,250	2,877
Mature after one year through two years	0	0
Mature over two years	344	366
Fair Value	2,594	3,243
Municipal/provincial bonds and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mature within one year	1,961	2,002
Mature after one year through two years	0	2,003
Mature over two years	0	0
Fair Value	1,961	4,005
Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mature within one year	105,200	97,438
Mature after one year through two years	114,853	146,197
Mature over two years	107,029	153,802
Fair Value	$ 327,082	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