Statutory Financial Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statutory Accounting Practices [Line Items]
Dividends available to be paid	$ 4,100
Approximate increase in statutory capital and surplus resulting from discount of certain A&E liabilities	144	$ 158
Minimum statutory capital and surplus required to satisfy regulatory requirements	14,500	14,800
PropertyAndCasualtySubsidiaries [Member]
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	20,072	25,805
Statutory net income	2,770	3,378	$ 3,333
LifeSubsidiaries [Member] [Member]
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	1,216	1,463
Statutory net income	$ (148)	$ (248)	$ 409