Accumulated Other Comprehensive Loss and Shareholders' Equity - Changes in Shareholders' Equity (Deficit) (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period	$ (79)	$ (20)	$ 703	$ 1,240	$ 1,603	$ 2,225	$ 703	$ 2,225
Net (loss) income	100	(234)	31	387	232	375	(103)	994
Other comprehensive loss	162	131	(378)	(178)	34	31	(85)	(113)
Dividends			(156)	(157)	(159)	(139)
Share-based compensation plans	46	44	(55)	46	30	(62)
Purchase of treasury stock			(150)	(500)	(500)	(828)
Balance at end of period	229	(79)	$ (20)	$ 838	$ 1,240	$ 1,603	229	838
Cash dividends (in USD per share)			$ 0.48	$ 0.48	$ 0.48	$ 0.41
Cumulative Effect, Period of Adoption, Adjustment | Adoption of ASU 2016-13
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period			$ (15)				(15)
Cumulative Effect, Period of Adoption, Adjustment | Adoption of ASU 2016-02
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period						$ 1		1
Class A Common Stock
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period	$ 5	$ 5	$ 5	$ 5	$ 5	$ 5	$ 5	$ 5
Balance at beginning of period (in shares)	324.3	324.2	324.0	330.6	334.1	339.1	324.0	339.1
Share-based compensation plans (in shares)	0.0	0.1	1.2	0.1	0.2	1.7
Purchase of treasury stock (in shares)			(1.0)	(3.8)	(3.7)	(6.7)
Balance at end of period	$ 5	$ 5	$ 5	$ 5	$ 5	$ 5	$ 5	$ 5
Balance at end of period (in shares)	324.3	324.3	324.2	326.9	330.6	334.1	324.3	326.9
Class A Common Stock | Cumulative Effect, Period of Adoption, Adjustment | Adoption of ASU 2016-13
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period			$ 0				$ 0
Class A Common Stock | Cumulative Effect, Period of Adoption, Adjustment | Adoption of ASU 2016-02
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period						$ 0		$ 0
Additional Paid-in- Capital
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period	$ 5,753	$ 5,711	5,800	$ 5,729	$ 5,706	5,814	5,800	5,814
Share-based compensation plans	45	42	(89)	44	23	(108)
Balance at end of period	5,798	5,753	5,711	5,773	5,729	5,706	5,798	5,773
Additional Paid-in- Capital | Cumulative Effect, Period of Adoption, Adjustment | Adoption of ASU 2016-13
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period			0				0
Additional Paid-in- Capital | Cumulative Effect, Period of Adoption, Adjustment | Adoption of ASU 2016-02
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period						0		0
Retained Earnings
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period	9,270	9,504	9,644	9,292	9,219	8,982	9,644	8,982
Net (loss) income	100	(234)	31	387	232	375
Dividends			(156)	(157)	(159)	(139)
Balance at end of period	9,370	9,270	9,504	9,522	9,292	9,219	9,370	9,522
Retained Earnings | Cumulative Effect, Period of Adoption, Adjustment | Adoption of ASU 2016-13
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period			(15)				(15)
Retained Earnings | Cumulative Effect, Period of Adoption, Adjustment | Adoption of ASU 2016-02
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period						1		1
Treasury Stock, at Cost
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period	(14,499)	(14,501)	(14,385)	(13,460)	(12,967)	(12,185)	(14,385)	(12,185)
Share-based compensation plans	1	2	34	2	7	46
Purchase of treasury stock			(150)	(500)	(500)	(828)
Balance at end of period	(14,498)	(14,499)	(14,501)	(13,958)	(13,460)	(12,967)	(14,498)	(13,958)
Treasury Stock, at Cost | Cumulative Effect, Period of Adoption, Adjustment | Adoption of ASU 2016-13
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period			0				0
Treasury Stock, at Cost | Cumulative Effect, Period of Adoption, Adjustment | Adoption of ASU 2016-02
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period						0		0
Accumulated Other Comprehensive Loss
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period	(608)	(739)	(361)	(326)	(360)	(391)	(361)	(391)
Other comprehensive loss	162	131	(378)	(178)	34	31
Balance at end of period	$ (446)	$ (608)	(739)	$ (504)	$ (326)	(360)	(446)	(504)
Accumulated Other Comprehensive Loss | Cumulative Effect, Period of Adoption, Adjustment | Adoption of ASU 2016-13
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period			$ 0				$ 0
Accumulated Other Comprehensive Loss | Cumulative Effect, Period of Adoption, Adjustment | Adoption of ASU 2016-02
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period						$ 0		$ 0