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, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period	$ 796	$ 234	$ 430	$ (79)	$ (20)	$ 703	$ 430	$ 703
Net income (loss)	220	422	(11)	100	(234)	31	631	(103)
Other comprehensive income (loss)	(138)	96	(155)	162	131	(378)	(197)	(85)
Dividends						(156)
Stock-based compensation plans	40	44	(30)	46	44	(55)
Purchase of treasury stock						(150)
Balance at end of period	918	796	234	229	(79)	$ (20)	918	229
Accounting standards update						Accounting Standards Update 2016-02 [Member]
Cash dividends (in USD per share)						$ 0.48
Cumulative Effect, Period of Adoption, Adjustment
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period						$ (15)		(15)
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)	325.6	325.6	324.4	324.3	324.2	324.0	324.4	324.0
Stock-based compensation plans (in shares)	0.1		1.2		0.1	1.2
Purchase of treasury stock (in shares)						(1.0)
Balance at end of period	$ 5	$ 5	$ 5	$ 5	$ 5	$ 5	$ 5	$ 5
Balance at end of period (in shares)	325.7	325.6	325.6	324.3	324.3	324.2	325.7	324.3
Additional Paid-in-Capital
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period	$ 5,830	$ 5,787	$ 5,851	$ 5,753	$ 5,711	$ 5,800	$ 5,851	$ 5,800
Stock-based compensation plans	39	43	(64)	45	42	(89)
Balance at end of period	5,869	5,830	5,787	5,798	5,753	5,711	5,869	5,798
Retained Earnings
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period	9,618	9,195	9,206	9,270	9,504	9,644	9,206	9,644
Net income (loss)	220	422	(11)	100	(234)	31
Dividends						(156)
Stock-based compensation plans		1
Balance at end of period	9,838	9,618	9,195	9,370	9,270	9,504	9,838	9,370
Retained Earnings | Cumulative Effect, Period of Adoption, Adjustment
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period						(15)		(15)
Treasury Stock, at Cost
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period	(14,463)	(14,463)	(14,497)	(14,499)	(14,501)	(14,385)	(14,497)	(14,385)
Stock-based compensation plans	1		34	1	2	34
Purchase of treasury stock						(150)
Balance at end of period	(14,462)	(14,463)	(14,463)	(14,498)	(14,499)	(14,501)	(14,462)	(14,498)
Accumulated Other Comprehensive Loss
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period	(194)	(290)	(135)	(608)	(739)	(361)	(135)	(361)
Other comprehensive income (loss)	(138)	96	(155)	162	131	(378)
Balance at end of period	$ (332)	$ (194)	$ (290)	$ (446)	$ (608)	$ (739)	$ (332)	$ (446)