Equity - Statements of Equity with dividends per share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Balance		$ 2,741			$ 2,741
Net income	$ 67		$ 107		145	$ 209
Balance	$ 2,666				2,666
Dividends declared, common stock (in dollars per share)	$ 0.63	$ 0.63	$ 0.625	$ 0.625
Common Stock
Balance	$ 1	$ 1	$ 1	$ 1	1	1
Balance	1	1	1	1	1	1
Additional Paid-in Capital
Balance	1,142	1,137	1,137	1,096	1,137	1,096
Repurchases of common stock, net				32		32
Share-based compensation, net of issuance	1	5	1	9	6	10
Balance	1,143	1,142	1,138	1,137	1,143	1,138
Treasury Stock
Balance	(1,028)	(1,040)	(1,050)	(1,091)	(1,040)	(1,091)
Repurchases of common stock, net				31		31
Share-based compensation, net of issuance	1	12	3	10	13	13
Balance	(1,027)	(1,028)	(1,047)	(1,050)	(1,027)	(1,047)
Accumulated Other Comprehensive Loss
Balance	(1,322)	(1,158)	(1,160)	(1,154)	(1,158)	(1,154)
Other comprehensive income (loss)	15	(164)	8	(6)	(149)	2
Balance	(1,307)	(1,322)	(1,152)	(1,160)	(1,307)	(1,152)
Retained Earnings
Balance	3,813	3,780	3,594	3,536	3,780	3,536
Net income	66	75	105	100	141	205
Dividends declared, common stock	(43)	(42)	(43)	(42)	(85)	(85)
Balance	3,836	3,813	3,656	3,594	3,836	3,656
Non-Controlling Interests
Balance	21	21	22	20	21	20
Net income	1	3	2	2	4	4
Dividends declared, common stock	(3)		(4)		(3)	(4)
Other comprehensive income (loss)	1	(3)	(4)		(2)	(4)
Balance	$ 20	$ 21	$ 16	$ 22	$ 20	$ 16