Investments - Contractual Maturities of Debt Securities and Other Investments (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Fair Value/Carrying Value	$ 37,860	$ 37,700	$ 37,660
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than one year	3,274
One to two years	3,702
Two to three years	1,947
Available-for-sale debt securities, Fair Value/Carrying Value	8,923		9,384
Municipal Fixed-Rate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
One to two years	934
Available-for-sale debt securities, Fair Value/Carrying Value	934		930
Asset-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than one year	101
One to two years	389
Two to three years	1,559
Three to five years	2,174
Five to ten years	1,505
More than ten years	265
Available-for-sale debt securities, Fair Value/Carrying Value	5,993		6,890
Mortgage/Agency-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
One to two years	584
Two to three years	1,769
Three to five years	107
Five to ten years	1,655
More than ten years	4,352
Available-for-sale debt securities, Fair Value/Carrying Value	8,467		6,962
U.S. Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than one year	61
One to two years	5,376
Two to three years	7,285
Three to five years	379
Available-for-sale debt securities, Fair Value/Carrying Value	13,101		$ 12,323
Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than one year	442
Available-for-sale debt securities, Fair Value/Carrying Value	$ 442