Stockholders' Equity - Changes in Each Component of Accumulated Other Comprehensive Income of the Parent (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance		$ (1,342)
Other comprehensive income (loss):
Ending Balance		(1,362)	$ (1,342)
Accounting Standards Update 2016-01 [Member]
Other comprehensive income (loss):
Adoption of new accounting standard, January 1			0		$ 2
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance		(670)	(646)	$ (608)
Other comprehensive income (loss):
Currency translation adjustments		(48)	(22)	(43)
Holding loss on net investment hedge		(3)	(2)
Elimination due to sale of subsidiary				2
Tax (expense) benefit				3
Other comprehensive income (loss) attributable to the parent company		(51)	(24)	(38)
Ending Balance		(721)	(670)	(646)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance		(64)	(34)	(4)
Other comprehensive income (loss):
Holding gains and losses		66	(162)	(16)
Reclassification of amount to net income	[1]	(56)	128	(14)
Tax (expense) benefit			4
Other comprehensive income (loss) attributable to the parent company		10	(30)	(30)
Ending Balance		(54)	(64)	(34)
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance		2	0	2
Other comprehensive income (loss):
Holding gains and losses			1	3
Reclassification of amount to net income	[1]			(7)
Elimination due to sale of subsidiary				2
Tax (expense) benefit			1
Other comprehensive income (loss) attributable to the parent company		0	2	(2)
Ending Balance		0	2	0
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] | Accounting Standards Update 2016-01 [Member]
Other comprehensive income (loss):
Adoption of new accounting standard, January 1			(2)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance		(610)	(604)	(564)
Other comprehensive income (loss):
Net actuarial losses		(8)	(28)	(88)
Curtailment gain			1
Reclassification adjustment for net actuarial losses included in net periodic benefit cost	[2]	34	30	26
Elimination due to sale of subsidiary				1
Other		2
Tax (expense) benefit		(5)	(9)	21
Other comprehensive income (loss) attributable to the parent company		23	(6)	(40)
Ending Balance		(587)	(610)	(604)
AOCI Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance		(1,342)	(1,284)	(1,174)
Other comprehensive income (loss):
Currency translation adjustments		(48)	(22)	(43)
Holding loss on net investment hedge		(3)	(2)
Holding gains and losses		66	(161)	(13)
Reclassification of amount to net income	[1]	(56)	128	(21)
Net actuarial losses		(8)	(28)	(88)
Curtailment gain			1
Reclassification adjustment for net actuarial losses included in net periodic benefit cost	[2]	34	30	26
Elimination due to sale of subsidiary				5
Other		2
Tax (expense) benefit		(5)	(4)	24
Other comprehensive income (loss) attributable to the parent company		(18)	(58)	(110)
Ending Balance		$ (1,362)	(1,342)	$ (1,284)
AOCI Attributable to Parent [Member] | Accounting Standards Update 2016-01 [Member]
Other comprehensive income (loss):
Adoption of new accounting standard, January 1			$ (2)

[1] reclassifications from AOCI were included in other income (expense), net.

[2] See Note 12 for additional details.