Investments - Summary of Investment Portfolio (Detail) - Credit Concentration Risk [Member]	12 Months Ended
	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Concentration risk percentage	100.00%
Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Concentration risk percentage	1.00%
Fixed Maturities [Member] | Corporate securities [Member] | External Credit Rating, Investment Grade [Member]
Schedule of Available-for-sale Securities [Line Items]
Concentration risk percentage	79.00%
Fixed Maturities [Member] | Corporate securities [Member] | External Credit Rating, Non Investment Grade [Member]
Schedule of Available-for-sale Securities [Line Items]
Concentration risk percentage	3.00%
Fixed Maturities [Member] | Securities of state and municipal governments [Member] | External Credit Rating, Investment Grade [Member]
Schedule of Available-for-sale Securities [Line Items]
Concentration risk percentage	10.00%
Fixed Maturities [Member] | Government-sponsored enterprises [Member] | External Credit Rating, Investment Grade [Member]
Schedule of Available-for-sale Securities [Line Items]
Concentration risk percentage	2.00%
Fixed Maturities [Member] | Other [Member] | External Credit Rating, Investment Grade [Member]
Schedule of Available-for-sale Securities [Line Items]
Concentration risk percentage	1.00%
Fixed Maturities [Member] | Other [Member] | External Credit Rating, Non Investment Grade [Member]
Schedule of Available-for-sale Securities [Line Items]
Concentration risk percentage	1.00%
Policy Loans [Member]
Schedule of Available-for-sale Securities [Line Items]
Concentration risk percentage	3.00%