Liability for Unpaid Claims and Claim Adjustment Expenses - Summary of Incurred and Paid Claims Development as Supplementary Information - Health (Detail) $ in Thousands	Dec. 31, 2019 USD ($) claim	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Claims Development [Line Items]
Liabilities for claims and claim adjustment expenses, net of reinsurance	$ 995,986
Health
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	226,198
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	205,265
All outstanding liabilities before period one, net of reinsurance	4,927
Liabilities for claims and claim adjustment expenses, net of reinsurance	25,860
Health | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	41,595	$ 41,514	$ 41,513	$ 45,167	$ 34,069
IBNR plus expected development	$ 0
Cumulative number of reported claims | claim	32,535
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 41,542	41,462	41,436	41,491	$ 23,574
Health | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	37,233	37,164	41,236	36,198
IBNR plus expected development	$ 0
Cumulative number of reported claims | claim	28,721
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 37,191	37,115	37,040	$ 24,357
Health | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	35,466	39,930	41,544
IBNR plus expected development	$ 1
Cumulative number of reported claims | claim	31,389
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 35,420	35,392	$ 25,358
Health | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	63,729	64,686
IBNR plus expected development	$ 6,005
Cumulative number of reported claims | claim	31,713
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 57,759	$ 34,894
Health | Accident Year 2019
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	48,175
IBNR plus expected development	$ 14,212
Cumulative number of reported claims | claim	28,826
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 33,353