Investments - Breakdown of Investments with Unrealized Losses (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule of Available-for-sale Securities [Line Items]
Continuous Unrealized Loss Position for Less than 12 Months, Fair Value	$ 3,378	$ 8,965
Continuous Unrealized Loss Position for Less than 12 Months, Unrealized Losses	(7)	(19)
Continuous Unrealized Loss Position for 12 Months or Greater, Fair Value		136
Continuous Unrealized Loss Position for 12 Months or Greater, Unrealized Losses		(2)
Total Fair Value	3,378	9,101
Total Unrealized Losses	(7)	(21)
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Continuous Unrealized Loss Position for Less than 12 Months, Fair Value	336	203
Total Fair Value	336	203
Municipal Fixed-Rate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Continuous Unrealized Loss Position for Less than 12 Months, Fair Value	310	930
Total Fair Value	310	930
Asset-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Continuous Unrealized Loss Position for Less than 12 Months, Fair Value	2	797
Continuous Unrealized Loss Position for Less than 12 Months, Unrealized Losses		(3)
Total Fair Value	2	797
Total Unrealized Losses		(3)
Mortgage/Agency-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Continuous Unrealized Loss Position for Less than 12 Months, Fair Value	2,078	2,594
Continuous Unrealized Loss Position for Less than 12 Months, Unrealized Losses	(6)	(6)
Continuous Unrealized Loss Position for 12 Months or Greater, Fair Value		136
Continuous Unrealized Loss Position for 12 Months or Greater, Unrealized Losses		(2)
Total Fair Value	2,078	2,730
Total Unrealized Losses	(6)	(8)
U.S. Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Continuous Unrealized Loss Position for Less than 12 Months, Fair Value	350	4,070
Continuous Unrealized Loss Position for Less than 12 Months, Unrealized Losses		(9)
Total Fair Value	350	4,070
Total Unrealized Losses		(9)
Foreign Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Continuous Unrealized Loss Position for Less than 12 Months, Fair Value	302	371
Continuous Unrealized Loss Position for Less than 12 Months, Unrealized Losses	(1)	(1)
Total Fair Value	302	371
Total Unrealized Losses	$ (1)	$ (1)

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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