Investments - Additional Information (Detail) $ in Millions	Mar. 31, 2016 USD ($) Issue	Dec. 31, 2015 Issue
Gain (Loss) on Investments [Line Items]
Total issues of fixed-maturities and equities | Issue	1,572	1,568
Fixed Maturities [Member]
Gain (Loss) on Investments [Line Items]
Fair value of securities previously impaired | $	$ 57
Percentage of investments previously impaired (less than)	1.00%