Fair Value - Additional Information (Detail) - USD ($)	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023
Fair Value, Inputs, Level 1
Fair Value Measurements [Line Items]
Vendor quoted prices, percent of FV hierarchy level	93.00%	93.00%	93.00%
Fair Value, Inputs, Level 2
Fair Value Measurements [Line Items]
Vendor quoted prices, percent of FV hierarchy level	99.00%	100.00%	99.00%
Dealer quoted prices, percent of FV hierarchy level	1.00%		1.00%
Fair Value, Inputs, Level 3 | Total fixed maturities
Fair Value Measurements [Line Items]
Number of securities	1	1	0