Accumulated Other Comprehensive Income - Reclassifications Out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest and other, net									$ (114)	$ 496	$ 11
Income from continuing operations before income taxes									2,207	2,718	2,275
Income tax provision					$ 445				(415)	(190)	(3,288)
Income (loss) from continuing operations	$ 558	$ 310	$ 403	$ 521	763	$ 720	$ 638	$ 407	1,792	2,528	(1,013)
Income (loss) from discontinued operations, net of income taxes	(2)	0	(1)	(3)	(3)	1	4	0	(6)	2	(4)
Net income (loss)	$ 556	$ 310	$ 402	$ 518	$ 760	$ 721	$ 642	$ 407	1,786	2,530	$ (1,017)
Amount of Gain (Loss) Reclassified from AOCI
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss)									64	(7)
Amount of Gain (Loss) Reclassified from AOCI | Gains (losses) on cash flow hedges - foreign exchange contracts | Foreign Exchange Contract
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenues									81	(8)
Income from continuing operations before income taxes									81	(8)
Income tax provision									(17)	2
Income (loss) from continuing operations									64	(6)
Income (loss) from discontinued operations, net of income taxes									0	0
Net income (loss)									64	(6)
Amount of Gain (Loss) Reclassified from AOCI | Unrealized gains (losses) on investments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest and other, net									0	(1)
Income from continuing operations before income taxes									0	(1)
Income tax provision									0	0
Net income (loss)									$ 0	$ (1)