Investments - Summary of Amortized Cost, Allowance for Credit Loss, Gross Unrealized Gains and Losses, and Estimated Fair Value of Available-for-Sale Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities, Cost or Amortized Cost	$ 98,669		$ 199,954
Fixed-maturity securities, Allowance for Credit Loss	(526)	$ (439)	0
Fixed-maturity securities, Gross Unrealized Gain	2,329		2,906
Fixed-maturity securities, Gross Unrealized Loss	(479)		(21)
Fixed-maturity securities, Estimated Fair Value	99,993		202,839
Fixed-Maturity Securities [Member] \| U.S. Treasury and U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities, Cost or Amortized Cost	12,146		26,220
Fixed-maturity securities, Gross Unrealized Gain	296		78
Fixed-maturity securities, Gross Unrealized Loss			(3)
Fixed-maturity securities, Estimated Fair Value	12,442		26,295
Fixed-Maturity Securities [Member] \| Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities, Cost or Amortized Cost	73,662		157,155
Fixed-maturity securities, Allowance for Credit Loss	(526)
Fixed-maturity securities, Gross Unrealized Gain	1,664		2,212
Fixed-maturity securities, Gross Unrealized Loss	(392)		(3)
Fixed-maturity securities, Estimated Fair Value	74,408		159,364
Fixed-Maturity Securities [Member] \| State, Municipalities, and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities, Cost or Amortized Cost	5,832		7,763
Fixed-maturity securities, Gross Unrealized Gain	89		149
Fixed-maturity securities, Gross Unrealized Loss	(12)
Fixed-maturity securities, Estimated Fair Value	5,909		7,912
Fixed-Maturity Securities [Member] \| Exchange-Traded Debt [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities, Cost or Amortized Cost	6,994		8,698
Fixed-maturity securities, Gross Unrealized Gain	280		462
Fixed-maturity securities, Gross Unrealized Loss	(74)		(15)
Fixed-maturity securities, Estimated Fair Value	7,200		9,145
Fixed-Maturity Securities [Member] \| Redeemable Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities, Cost or Amortized Cost	35		118
Fixed-maturity securities, Gross Unrealized Gain			5
Fixed-maturity securities, Gross Unrealized Loss	(1)
Fixed-maturity securities, Estimated Fair Value	$ 34		$ 123

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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