Liability for Unpaid Claims and Claim Adjustment Expenses - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Insurance [Abstract]
Description of increase (decrease) in claims and claim adjustment expenses	The net and gross reserve calculations have shown favorable development as a result of favorable loss emergence compared to what was implied by the loss development patterns used in the original estimation of losses in prior years.
Decrease in claims and claim adjustments expenses amount	$ 57,979	$ 19,852	$ 75,632
Short-duration health insurance claims	$ 21,379
Percentage of IBNR reserves applied to paid adjusting and other expense to paid loss	100.00%