Consolidated Statements of Changes in Equity and Redeemable Non-Controlling Interest - USD ($) $ in Millions	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Non- Controlling Interest in Consolidated Subsidiaries	Redeemable Non-Controlling Interest
Beginning Balance (in shares) at Dec. 31, 2017		600,000,000	17,000,000
Beginning Balance at Dec. 31, 2017	$ 16,985	$ 6	$ (1,076)	$ 11,392	$ 6,858	$ (223)	$ 28	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income	33					33
Exercise of common stock options	4			4
Repurchases of common stock (in shares)			(4,000,000)
Repurchases of common stock	(300)		$ (300)
Payments relating to treasury shares (in shares)			(1,000,000)
Payments relating to treasury shares	(72)		$ (72)
Stock-based compensation	32			32
Issuance of restricted stock (in shares)		3,000,000
Issuance of restricted stock	0
Distributions of profits	(10)						(10)
Dividends paid to stockholders	(140)				(140)
Net income attributable to non-controlling interest	0				(10)		10
Net income	474				474
Ending Balance (in shares) at Mar. 31, 2018		603,000,000	22,000,000
Ending Balance at Mar. 31, 2018	$ 17,006	$ 6	$ (1,448)	11,428	7,182	(190)	28	0
Beginning Balance (in shares) at Dec. 31, 2018	604,000,000	604,000,000	35,000,000
Beginning Balance at Dec. 31, 2018	$ 17,231	$ 6	$ (2,354)	11,547	8,317	(315)	30	71
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income	25					25
Exercise of common stock options	5			5
Repurchases of common stock (in shares)			(6,000,000)
Repurchases of common stock	(440)		$ (440)
Payments relating to treasury shares	(57)		$ (57)
Stock-based compensation	33			33
Issuance under the employee stock purchase plan	12			12
Issuance of restricted stock (in shares)		2,000,000
Issuance of restricted stock	0
Distributions of profits	(14)						(14)
Dividends paid to stockholders	(157)				(157)
Net income attributable to non-controlling interest	0				(8)		8
Net income	$ 492				492
Ending Balance (in shares) at Mar. 31, 2019	606,000,000	606,000,000	41,000,000
Ending Balance at Mar. 31, 2019	$ 17,130	$ 6	$ (2,851)	$ 11,597	$ 8,644	$ (290)	$ 24	$ 71