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Investments - Contractual Maturities of Debt Securities and Other Investments (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Fair Value/Carrying Value	$ 44,480	$ 45,116
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than one year	436
One to two years	4,575
Two to three years	7,518
Three to five years	2,472
Available-for-sale debt securities, Fair Value/Carrying Value	15,001	11,885
Municipal Fixed-Rate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than one year	529
One to two years	496
Two to three years	1,103
Three to five years	409
Available-for-sale debt securities, Fair Value/Carrying Value	2,537	2,884
Asset-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than one year	1
Two to three years	50
Three to five years	1,749
Five to ten years	866
More than ten years	1,335
Available-for-sale debt securities, Fair Value/Carrying Value	4,001	6,708
Mortgage/Agency-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than one year	254
One to two years	1,865
Two to three years	1,199
Three to five years	165
Five to ten years	2,213
More than ten years	5,343
Available-for-sale debt securities, Fair Value/Carrying Value	11,039	11,644
U.S. Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than one year	735
One to two years	7,240
Two to three years	1,188
Three to five years	1,660
Available-for-sale debt securities, Fair Value/Carrying Value	10,823	9,875
Foreign Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Two to three years	546
Available-for-sale debt securities, Fair Value/Carrying Value	546	1,337
Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than one year	533
Available-for-sale debt securities, Fair Value/Carrying Value	$ 533	$ 533

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Amount of available-for-sale debt securities at fair value maturing after one year through two years.

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