Shareholders Equity and Dividend Restrictions (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statutory Accounting Practices [Line Items]
Statutory net income	$ 2,002,000,000	$ 1,631,000,000	$ 1,520,000,000
Statutory Surplus	7,487,000,000	6,316,000,000	6,109,000,000
State And Foreign Jurisdictions [Member]
Statutory Accounting Practices [Line Items]
Minimum statutory surplus required by regulators	2,500,000,000
Restricted net assets of the Company	8,800,000,000
Amount certain of the Company's life insurance subisdiaries are permitted to loan up to the parent company without prior approval	1,000,000,000
Impact of accounting practice permitted by foreign jurisdiction on surplus	200,000,000
State And Foreign Jurisdictions [Member] | Maximum [Member]
Statutory Accounting Practices [Line Items]
Maximum dividend distribution the Company's life insurance and HMO subsidiaries may make next year	1,000,000,000
State Departments Of Insurance [Member]
Statutory Accounting Practices [Line Items]
Statutory carrying value of investments on deposit with state departments of insurance	$ 400,000,000