Components of Equity (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Stockholders Equity Note [Line Items]
Beginning Balance	$ 7,325	$ 7,566
Net income (loss)	(3)	186
Net income (loss)	(3)	187
Issuance of common stock for comprehensive stock plans, net	(5)	(2)
Repurchase of common stock	(147)
Dividends declared on common stock	(141)	(148)
Distributions to non- controlling interests		(67)
Changes in ownership and other	57	(16)
Other comprehensive income/(loss)	(16)
Ending Balance	7,070	7,520
Common Stock
Stockholders Equity Note [Line Items]
Beginning Balance	7	7
Ending Balance	7	7
Additional Paid-in Capital
Stockholders Equity Note [Line Items]
Beginning Balance	7,675	8,156
Issuance of common stock for comprehensive stock plans, net	(5)	(2)
Repurchase of common stock	(147)
Changes in ownership and other	57	(16)
Ending Balance	7,580	8,138
Accumulated Other Comprehensive Income (Loss)
Stockholders Equity Note [Line Items]
Beginning Balance	(56)	(59)
Other comprehensive income/(loss)	(16)
Ending Balance	(72)	(59)
Retained Earnings / (Deficit)
Stockholders Equity Note [Line Items]
Beginning Balance	(307)	(610)
Net income (loss)	(3)	186
Dividends declared on common stock	(141)	(148)
Changes in ownership and other		(1)
Ending Balance	(451)	(573)
Non-redeemable, non-controlling interests
Stockholders Equity Note [Line Items]
Beginning Balance	6	72
Net income (loss)		1
Distributions to non- controlling interests		(67)
Changes in ownership and other		1
Ending Balance	6	7
Redeemable, non-controlling interests
Stockholders Equity Note [Line Items]
Beginning Balance	142	128
Net income (loss)		2
Distributions to non- controlling interests	(2)	(2)
Changes in ownership and other	(56)	19
Ending Balance	$ 84	$ 147