Stock-Based Compensation Nonvested Shares and Other (Details) - Common Shares - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Long-Term Incentive Plans \| Restricted Stock Units
Stock based compensation, Nonvested shares rollforward, number of shares
Nonvested stock units, begin of period - Number of shares	1,194,000
Granted number of shares	571,000
Vested number of shares	(348,000)
Forfeited number of shares	(107,000)
Nonvested stock units, end of period - Number of shares	1,310,000	1,194,000
Stock based compensation, Nonvested shares weighted average grant date fair value
Nonvested stock units - begin of period weighted average grant date fair value	$ 36.70
Granted weighted average grant date fair value	43.32	$ 37.24	$ 41.24
Vested weighted average grant date fair value	31.52
Forfeited weighted average grant date fair value	39.28
Nonvested stock units - end of period weighted average grant date fair value	$ 40.74	$ 36.70
Fair value of vested stock units	$ 15	$ 13	$ 11
Long-Term Incentive Plans \| Deferred Compensation Stock Units
Stock based compensation, Nonvested shares weighted average grant date fair value
Granted weighted average grant date fair value	$ 41.31	$ 35.96
Shares issued and granted under stock compensation plans
Vested number of shares, unissued	7,000
Long-Term Incentive Plans \| Deferred Compensation Stock Units \| Maximum
Stock based compensation, Nonvested shares weighted average grant date fair value
Fair value of vested stock units	$ 1	$ 1
Shares issued and granted under stock compensation plans
Vested number of shares, unissued, fair value	$ 1
Non-Employee Directors' Plan
Shares issued and granted under stock compensation plans
Shares issued	13,000	15,000	14,200

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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Gross number of shares (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP). Shares issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period but were not issued.

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