Current Expected Credit Losses - Available-for-Sale Debt Securities in Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Jan. 01, 2020
Schedule of Available-for-sale Securities [Line Items]
Continuous Unrealized Loss Position for Less than 12 Months, Fair Value	$ 4,864	$ 8,965
Continuous Unrealized Loss Position for Less than 12 Months, Unrealized Losses	(12)	(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	4,864	9,101
Total Unrealized Losses	(12)	(21)
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Continuous Unrealized Loss Position for Less than 12 Months, Fair Value		203
Total Fair Value		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	394	930
Continuous Unrealized Loss Position for Less than 12 Months, Unrealized Losses	(1)
Total Fair Value	394	930
Total Unrealized Losses	(1)
Asset-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Continuous Unrealized Loss Position for Less than 12 Months, Fair Value	396	797
Continuous Unrealized Loss Position for Less than 12 Months, Unrealized Losses		(3)
Total Fair Value	396	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	3,199	2,594
Continuous Unrealized Loss Position for Less than 12 Months, Unrealized Losses	(11)	(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	3,199	2,730
Total Unrealized Losses	(11)	(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	800	4,070
Continuous Unrealized Loss Position for Less than 12 Months, Unrealized Losses		(9)
Total Fair Value	800	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	75	371
Continuous Unrealized Loss Position for Less than 12 Months, Unrealized Losses		(1)
Total Fair Value	$ 75	371
Total Unrealized Losses		$ (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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