Liability for Future Policy Benefits and Policyholder Account Balances - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019
Liability for Claims and Claims Adjustment Expense [Line Items]
Interest credited investment type contracts low end (as percent)	1.00%
Interest credited investment type contracts high end (as percent)	8.00%
First year interest credited annuity low end (as percent)	1.00%
First year interest credited annuity high end (as percent)	7.00%
Non Participating Life Insurance Policies | Minimum
Liability for Claims and Claims Adjustment Expense [Line Items]
Interest rate (as percent)	3.00%
Non Participating Life Insurance Policies | Maximum
Liability for Claims and Claims Adjustment Expense [Line Items]
Interest rate (as percent)	8.00%
Participating Life Insurance Policies | Minimum
Liability for Claims and Claims Adjustment Expense [Line Items]
Interest rate (as percent)	2.50%
Participating Life Insurance Policies | Maximum
Liability for Claims and Claims Adjustment Expense [Line Items]
Interest rate (as percent)	5.50%
Annuity | Minimum
Liability for Claims and Claims Adjustment Expense [Line Items]
Interest rate (as percent)	3.00%
Annuity | Maximum
Liability for Claims and Claims Adjustment Expense [Line Items]
Interest rate (as percent)	6.00%
Non Medical Health | Minimum
Liability for Claims and Claims Adjustment Expense [Line Items]
Interest rate (as percent)	3.50%
Non Medical Health | Maximum
Liability for Claims and Claims Adjustment Expense [Line Items]
Interest rate (as percent)	8.00%
Disabled Lives | Minimum
Liability for Claims and Claims Adjustment Expense [Line Items]
Interest rate (as percent)	3.00%
Disabled Lives | Maximum
Liability for Claims and Claims Adjustment Expense [Line Items]
Interest rate (as percent)	6.00%