Condensed Financial Information Of Registrant (Condensed Statements Of Cash Flows) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash provided by operating activities	$ 1,223	$ 382	$ 279
Purchases of investments	(1,015)us-gaap_PaymentsToAcquireInvestments	(790)us-gaap_PaymentsToAcquireInvestments	(696)us-gaap_PaymentsToAcquireInvestments
Sales and maturities of investments	406	579	590
Acquisitions, net of cash required	(136)	(63)	0
Net cash used in investing activities	(848)	(342)	(188)
Proceeds from borrowings	1,875	180	400
Payment of long-term debt and notes payable	(1,674)us-gaap_RepaymentsOfLongTermDebt	(41)us-gaap_RepaymentsOfLongTermDebt	(218)us-gaap_RepaymentsOfLongTermDebt
Proceeds from exercise of stock options	8	9	16
Common stock offering	0	15	0
Common stock repurchases	(29)	(19)	(13)
Debt issue costs	(7)us-gaap_PaymentsOfDebtIssuanceCosts	(4)us-gaap_PaymentsOfDebtIssuanceCosts	(4)us-gaap_PaymentsOfDebtIssuanceCosts
Purchase of noncontrolling interest	0	0	(14)
Excess tax benefits from stock compensation	19	6	11
Net cash provided by financing activities	198	154	179
Net (decrease) increase in cash and cash equivalents	572	194	270
Cash and cash equivalents, beginning of period	1,038	844	574
Cash and cash equivalents, end of period	1,610	1,038	844
Parent Company [Member]
Cash provided by operating activities	317	302	328
Net dividends from and capital contributions to subsidiaries	(384)	(417)	(540)
Purchases of investments	32	(12)	(7)
Sales and maturities of investments	14	10	30
Acquisitions, net of cash required	137	(67)	0
Net cash used in investing activities	(539)	(486)	(517)
Proceeds from borrowings	1,875	180	400
Payment of long-term debt and notes payable	1,650	(30)	(215)
Proceeds from exercise of stock options	8	9	16
Common stock offering	0	15	0
Common stock repurchases	29	(20)	(13)
Debt issue costs	7	(3)	(4)
Contributions from noncontrolling interest	6	8	1
Purchase of noncontrolling interest	0	0	(14)
Excess tax benefits from stock compensation	19	6	11
Net cash provided by financing activities	222	165	182
Net (decrease) increase in cash and cash equivalents	0	(19)	(7)
Cash and cash equivalents, beginning of period	3	22	29
Cash and cash equivalents, end of period	$ 3	$ 3	$ 22

Net dividends from and capital contributions to subsidiaries

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For the entity and the disposal group, cash includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the Entity may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Compensating balance arrangements that do not legally restrict the withdrawal or usage of cash amounts may be reported as Cash and Cash Equivalents, while legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or company statements of intention with regard to particular deposits are not generally reported as cash and cash equivalents.

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Amount of increase (decrease) in cash and cash equivalents. Cash and cash equivalents are the amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Includes effect from exchange rate changes.

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Amount of cash inflow from realized tax benefit related to deductible compensation cost reported on the entity's tax return for equity instruments in excess of the compensation cost for those instruments recognized for financial reporting purposes.

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Amount of cash inflow (outflow) from financing activities, including discontinued operations. Financing activity cash flows include obtaining resources from owners and providing them with a return on, and a return of, their investment; borrowing money and repaying amounts borrowed, or settling the obligation; and obtaining and paying for other resources obtained from creditors on long-term credit.

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Amount of cash inflow (outflow) from investing activities, including discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets.

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Amount of cash inflow (outflow) from operating activities, including discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities.

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The cash outflow to reacquire common stock during the period.

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The cash outflow paid to third parties in connection with debt origination, which will be amortized over the remaining maturity period of the associated long-term debt.

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The cash outflow associated with the purchase of noncontrolling interest during the period.

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The cash outflow associated with the acquisition of a controlling interest in another entity or an entity that is related to it but not strictly controlled (for example, an unconsolidated subsidiary, affiliate, joint venture or equity method investment).

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The cash outflow associated with the purchase of all investments (debt, security, other) during the period.

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The cash inflow from an entity that is affiliated with the entity by means of direct or indirect ownership.

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The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

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The cash inflow from the issuance of common stock, preferred stock, treasury stock, stock options, and other types of equity.

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The cash inflow associated with the sale, maturity and collection of all investments such as debt, security and so forth during the period.

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The cash inflow associated with the amount received from holders exercising their stock options. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

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The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

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