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				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period	$ 234	$ 430	$ (20)	$ 703	$ 430	$ 703
Net income (loss)	422	(11)	(234)	31	411	(203)
Other comprehensive income (loss)	96	(155)	131	(378)	(59)	(247)
Dividends				(156)
Stock-based compensation plans	44	(30)	44	(55)
Purchase of treasury stock				(150)
Balance at end of period	796	234	(79)	$ (20)	796	(79)
Accounting standards update				us-gaap:AccountingStandardsUpdate201602Member
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
Balance at beginning of period (in shares)	325.6	324.4	324.2	324.0	324.4	324.0
Stock-based compensation plans (in shares)		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
Balance at end of period (in shares)	325.6	325.6	324.3	324.2	325.6	324.3
Additional Paid-in-Capital
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period	$ 5,787	$ 5,851	$ 5,711	$ 5,800	$ 5,851	$ 5,800
Stock-based compensation plans	43	(64)	42	(89)
Balance at end of period	5,830	5,787	5,753	5,711	5,830	5,753
Retained Earnings
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period	9,195	9,206	9,504	9,644	9,206	9,644
Net income (loss)	422	(11)	(234)	31
Dividends				(156)
Stock-based compensation plans	1
Balance at end of period	9,618	9,195	9,270	9,504	9,618	9,270
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)	(14,497)	(14,501)	(14,385)	(14,497)	(14,385)
Stock-based compensation plans		34	2	34
Purchase of treasury stock				(150)
Balance at end of period	(14,463)	(14,463)	(14,499)	(14,501)	(14,463)	(14,499)
Accumulated Other Comprehensive Loss
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period	(290)	(135)	(739)	(361)	(135)	(361)
Other comprehensive income (loss)	96	(155)	131	(378)
Balance at end of period	$ (194)	$ (290)	$ (608)	$ (739)	$ (194)	$ (608)