Components of Equity (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Stockholders Equity Note [Line Items]
Beginning Balance	$ 6,722	$ 7,474	$ 7,325	$ 7,566
Net income (loss)	(313)	368	(668)	840
Net income (loss)	(313)	368	(668)	842
Issuance of common stock for comprehensive stock plans, net	6	4	7	6
Repurchase of common stock		(200)	(147)	(400)
Dividends declared on common stock		(144)	(141)	(438)
Distributions to non-controlling interests		(1)		(68)
Changes in ownership and other	(3)	10	54
Other comprehensive income/(loss)	(5)	(6)	(23)	(3)
Ending Balance	6,407	7,505	6,407	7,505
Common Stock
Stockholders Equity Note [Line Items]
Beginning Balance	7	7	7	7
Ending Balance	7	7	7	7
Additional Paid-in Capital
Stockholders Equity Note [Line Items]
Beginning Balance	7,586	7,948	7,675	8,156
Issuance of common stock for comprehensive stock plans, net	6	4	7	6
Repurchase of common stock		(200)	(147)	(400)
Changes in ownership and other	(3)	10	54
Ending Balance	7,589	7,762	7,589	7,762
Accumulated Other Comprehensive Income (Loss)
Stockholders Equity Note [Line Items]
Beginning Balance	(74)	(56)	(56)	(59)
Other comprehensive income/(loss)	(5)	(6)	(23)	(3)
Ending Balance	(79)	(62)	(79)	(62)
Retained Earnings / (Deficit)
Stockholders Equity Note [Line Items]
Beginning Balance	(802)	(432)	(307)	(610)
Net income (loss)	(313)	368	(668)	840
Dividends declared on common stock		(144)	(141)	(438)
Changes in ownership and other			1
Ending Balance	(1,115)	(208)	(1,115)	(208)
Non-redeemable, non-controlling interests
Stockholders Equity Note [Line Items]
Beginning Balance	5	7	6	72
Net income attributable to non-controlling interests				2
Distributions to non-controlling interests		(1)		(68)
Changes in ownership and other			(1)
Ending Balance	5	6	5	6
Redeemable, non-controlling interests
Stockholders Equity Note [Line Items]
Beginning Balance	81	141	142	128
Net income	(3)	4	(7)	9
Distributions to non-controlling interests		(2)		(5)
Changes in ownership and other	2	(10)	(53)	1
Ending Balance	$ 80	$ 133	$ 80	$ 133