Stockholders' Equity (Components of Accumulated Other Comprehensive Income) (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Net current period other comprehensive income (loss)		$ (399)	$ 26
Net current period other comprehensive income (loss)		$ 34	$ (4)
Dividends declared		$ 1.07	$ 1.03
Defined Benefit Pension Plans
Defined benefit and other postretirement benefit plans - Beginning balance		$ (979)	$ (1,017)
Other comprehensive income/(loss) before reclassifications		19	(7)
(Income)/loss reclassified from AOCI	[1]	10	3
Net current period other comprehensive income (loss)		29	(4)
Defined benefit and other postretirement benefit plans - Ending balance		(950)	(1,021)
Other Postretirement Benefit Plans
Defined benefit and other postretirement benefit plans - Beginning balance		(13)	12
Other comprehensive income/(loss) before reclassifications		5	0
(Income)/loss reclassified from AOCI	[1]	0	0
Net current period other comprehensive income (loss)		5	0
Defined benefit and other postretirement benefit plans - Ending balance		(8)	12
Unrealized Translation
Unrealized translation - Beginning balance		(2,271)	(2,297)
Other comprehensive income/(loss) before reclassifications		(386)	31
(Income)/loss reclassified from AOCI		0	0
Net current period other comprehensive income (loss)		(386)	31
Unrealized translation - Ending balance		(2,657)	(2,266)
Cash Flow Hedges and Other
Cash flow hedge and other - Beginning balance		(31)	3
Other comprehensive income/(loss) before reclassifications		31	(12)
(Income)/loss reclassified from AOCI		0	(5)
Net current period other comprehensive income (loss)		31	(17)
Cash flow hedge and other - Ending balance		$ 0	$ (14)

[1] Included in computation of net periodic benefit costs.