Statutory Accounting Practices - Combined Statutory Capital and Surplus and Net Income (Loss) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statutory Accounting Practices [Line Items]
Statutory Capital and Surplus	$ 90
Combined Continental Casualty Companies [Member]
Statutory Accounting Practices [Line Items]
Statutory Capital and Surplus	10,723	$ 11,155
Statutory Net Income	$ 1,148	914	$ 913
Life Company [Member]
Statutory Accounting Practices [Line Items]
Statutory Net Income		$ 37	$ 48