Statutory Accounting Practices - Combined Statutory Capital and Surplus and Net Income (Loss) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Combined Continental Casualty Companies [Member]
Statutory Accounting Practices [Line Items]
Statutory Capital and Surplus	$ 11,155	$ 11,137
Statutory Net Income	914	913	391
Life Company [Member]
Statutory Accounting Practices [Line Items]
Statutory Capital and Surplus		597
Statutory Net Income	$ 37	$ 48	$ 44