Supplemental Financial Statement Information (Components of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 120,331	$ 103,860	$ 86,977
Other comprehensive income (loss) before reclassifications	(398)	(1,106)	160
Amounts reclassified from AOCI	(130)	(795)	(258)
Other comprehensive income (loss)	(528)	(1,901)	(98)
Ending Balance	139,036	120,331	103,860
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(2,047)	(980)	16
Other comprehensive income (loss) before reclassifications	(599)	(1,067)	(996)
Amounts reclassified from AOCI	0	0	0
Other comprehensive income (loss)	(599)	(1,067)	(996)
Ending Balance	(2,646)	(2,047)	(980)
Unrealized Gains (Losses) on Available-for-Sale Investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(86)	421	50
Other comprehensive income (loss) before reclassifications	(314)	(715)	505
Amounts reclassified from AOCI	221	208	(134)
Other comprehensive income (loss)	(93)	(507)	371
Ending Balance	(179)	(86)	421
Unrealized Gains on Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	259	586	59
Other comprehensive income (loss) before reclassifications	515	676	651
Amounts reclassified from AOCI	(351)	(1,003)	(124)
Other comprehensive income (loss)	164	(327)	527
Ending Balance	423	259	586
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(1,874)	27	125
Ending Balance	$ (2,402)	$ (1,874)	$ 27