Statutory Financial Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statutory Accounting Practices [Line Items]
Dividends available to be paid	$ 6,100
Approximate increase in statutory capital and surplus resulting from discount of certain A&E liabilities	160	$ 169
Minimum statutory capital and surplus required to satisfy regulatory requirements	25,900	23,900
Statutory Accounting Practices, Permitted Practice, Amount	183	156
PropertyAndCasualtySubsidiaries [Member]
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	40,985	39,927
Statutory net income	7,499	8,178	$ 6,903
LifeSubsidiaries [Member] [Member]
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	1,310	1,515
Statutory net income	$ (111)	$ 49	$ 55