Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

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Amount of paid and unpaid common stock dividends declared with the form of settlement in cash, stock and payment-in-kind (PIK).

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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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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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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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Gross value of stock (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). Stock 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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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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Amount of stockholders' equity including the portion attributable to noncontrolling interests, after the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

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Number of shares that have been repurchased during the period and are being held in treasury.

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Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

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CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Millions	Total	Common shares [Member]	Additional paid-in capital [Member]	Retained earnings [Member]	Treasury shares [Member]	AOCI Attributable to Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of change in accounting policies \| Accounting Standards Update 2014-09 [Member]				$ (3)
Cumulative effect of change in accounting policies \| Cumulative effect of change in accounting policies - Recognition and measurement of financial instruments	$ (3)
Beginning balance, restated	6,289	$ 3	$ 7,765	10,348	$ (12,027)	$ 200
Beginning balance (in shares) at Dec. 31, 2016		154,759,904
Beginning balance at Dec. 31, 2016	6,292	$ 3	7,765	10,351	(12,027)	200
Comprehensive income (loss) [Abstract]
Net income	796			796
Other comprehensive income (loss), net of tax	99					99
Total comprehensive income	895
Dividends to shareholders	(250)			(250)
Repurchase of common shares (in shares)		(7,021,250)
Repurchase of common shares	(877)				(877)
Share-based compensation plans (in shares)		2,569,962
Share-based compensation plans	190		138		52
Ending balance (in shares) at Jun. 30, 2017		150,308,616.000000
Ending balance at Jun. 30, 2017	6,247	$ 3	7,903	10,894	(12,852)	299
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of change in accounting policies \| Cumulative effect of change in accounting policies - Recognition and measurement of financial instruments						(1)
Beginning balance (in shares) at Dec. 31, 2017		146,634,664
Beginning balance at Dec. 31, 2017	5,995	$ 3	8,085	11,326	(13,648)	229
Comprehensive income (loss) [Abstract]
Net income	1,056			1,056
Other comprehensive income (loss), net of tax	(407)					(407)
Total comprehensive income	649
Dividends to shareholders	(257)			(257)
Repurchase of common shares (in shares)		(5,978,029)
Repurchase of common shares	(900)				(900)
Share-based compensation plans (in shares)		1,563,776
Share-based compensation plans	145		86		59
Ending balance (in shares) at Jun. 30, 2018		142,220,411.000000
Ending balance at Jun. 30, 2018	5,632	$ 3	$ 8,171	12,126	$ (14,489)	(179)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of change in accounting policies \| Cumulative effect of change in accounting policies - Recognition and measurement of financial instruments	$ 0			$ 1		$ (1)