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No definition available.

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- Definition

The year when the debt instrument is scheduled to be fully repaid.

+ References

No definition available.

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- Definition

Represent the issuance amount of corporate debt.

+ References

No definition available.

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- Definition

Cash outflow used to repay debt and any associated redemption premiums, accrued interest and related fees and expenses.

+ References

No definition available.

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- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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No definition available.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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- Definition

Amount, after accumulated amortization, of debt discount.

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- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

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- Definition

Fair value of the amount outstanding under the credit facility.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Corporate Debt (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Corporate Debt (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Disclosure (Textuals) [Abstract]
Issuance of debt		$ 1,000
Gains (losses) on early extinguishment of debt	$ (58)	(58)	$ 0	$ (112)
Corporate Debt Securities [Member]
Debt Instrument [Line Items]
Face Value		1,000	1,003
Unamortized discount		(9)	(9)
Total corporate debt		991	994
Debt Disclosure (Textuals) [Abstract]
Gains (losses) on early extinguishment of debt		$ 58		(73)
Interest Bearing Total [Member] \| Corporate Debt Securities [Member]
Debt Instrument [Line Items]
Face Value			1,000
Unamortized discount			(9)
Total corporate debt			991
Senior Notes Interest Bearing Two And Nine Five Percent [Member]
Debt Instrument Interest Rate Stated Percentage [Abstract]
Debt instrument, exact maturity date		Aug. 24, 2022
Debt Disclosure (Textuals) [Abstract]
Issuance of debt		$ 600
Senior Notes Interest Bearing Two And Nine Five Percent [Member] \| Corporate Debt Securities [Member]
Debt Instrument [Line Items]
Face Value		600
Unamortized discount		(5)
Total corporate debt		$ 595
Debt Instrument Interest Rate Stated Percentage [Abstract]
Debt instrument maturity year		2022
Debt instrument, interest rate, stated percentage		2.95%
Senior Notes Interest Bearing Three And Eight Percent [Member]
Debt Instrument Interest Rate Stated Percentage [Abstract]
Debt instrument, exact maturity date		Aug. 24, 2027
Debt Disclosure (Textuals) [Abstract]
Issuance of debt		$ 400
Senior Notes Interest Bearing Three And Eight Percent [Member] \| Corporate Debt Securities [Member]
Debt Instrument [Line Items]
Face Value		400
Unamortized discount		(4)
Total corporate debt		$ 396
Debt Instrument Interest Rate Stated Percentage [Abstract]
Debt instrument maturity year		2027
Debt instrument, interest rate, stated percentage		3.80%
Senior Notes Interest Bearing Five And Three Seven Five Percent [Member]
Debt Disclosure (Textuals) [Abstract]
Redemption of Senior Note		$ 540
Senior Notes Interest Bearing Five And Three Seven Five Percent [Member] \| Corporate Debt Securities [Member]
Debt Instrument [Line Items]
Face Value			540
Unamortized discount			(5)
Total corporate debt			$ 535
Debt Instrument Interest Rate Stated Percentage [Abstract]
Debt instrument maturity year			2022
Debt instrument, interest rate, stated percentage			5.375%
Senior Notes Interest Bearing Four And Six Two Five Percent [Member]
Debt Disclosure (Textuals) [Abstract]
Issuance of debt				$ 460
Redemption of Senior Note		460
Senior Notes Interest Bearing Four And Six Two Five Percent [Member] \| Corporate Debt Securities [Member]
Debt Instrument [Line Items]
Face Value			$ 460
Unamortized discount			(4)
Total corporate debt			$ 456
Debt Instrument Interest Rate Stated Percentage [Abstract]
Debt instrument maturity year			2023
Debt instrument, interest rate, stated percentage			4.625%
Noninterest Bearing Convertible Debentures [Member] \| Corporate Debt Securities [Member]
Debt Instrument [Line Items]
Face Value			$ 3
Unamortized discount			0
Total corporate debt			$ 3
Debt Instrument Interest Rate Stated Percentage [Abstract]
Debt instrument maturity year			2019
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		300
Line of Credit Facility, Fair Value of Amount Outstanding		$ 0
Line of Credit Facility, Expiration Date		Jun. 23, 2020