Supplemental Financial Statement Information (Components of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019	Jan. 01, 2018	Jan. 01, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 177,628	$ 152,502	$ 139,036
Cumulative effect of accounting change				$ (34)	$ (697)	$ (15)
Other comprehensive income (loss) before reclassifications	1,528	(429)	1,212
Amounts excluded from the assessment of hedge effectiveness recorded in AOCI	(14)	26
Amounts reclassified from AOCI	(410)	(813)	198
Other comprehensive income (loss)	1,104	(1,216)	1,410
Ending Balance	201,442	177,628	152,502
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(1,884)	(1,103)	(2,646)
Other comprehensive income (loss) before reclassifications	(119)	(781)	1,543
Amounts excluded from the assessment of hedge effectiveness recorded in AOCI	0	0
Amounts reclassified from AOCI	0	0	0
Other comprehensive income (loss)	(119)	(781)	1,543
Ending Balance	(2,003)	(1,884)	(1,103)
Unrealized Gains (Losses) on Available-for-Sale Investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(688)	233	(179)
Other comprehensive income (loss) before reclassifications	1,611	88	307
Amounts excluded from the assessment of hedge effectiveness recorded in AOCI	0	0
Amounts reclassified from AOCI	(111)	(911)	105
Other comprehensive income (loss)	1,500	(823)	412
Ending Balance	812	(688)	233
Unrealized Gains (Losses) on Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	266	(122)	423
Other comprehensive income (loss) before reclassifications	36	264	(638)
Amounts excluded from the assessment of hedge effectiveness recorded in AOCI	(14)	26
Amounts reclassified from AOCI	(299)	98	93
Other comprehensive income (loss)	(277)	388	(545)
Ending Balance	(41)	266	(122)
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(2,306)	(992)	(2,402)
Cumulative effect of accounting change				(30)	(98)
Ending Balance	$ (1,232)	$ (2,306)	$ (992)
Accounting Standards Update 2016-01
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect of accounting change					(98)
Accounting Standards Update 2016-01 | Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect of accounting change					0
Accounting Standards Update 2016-01 | Unrealized Gains (Losses) on Available-for-Sale Investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect of accounting change					(98)
Accounting Standards Update 2016-01 | Unrealized Gains (Losses) on Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect of accounting change					$ 0
Accounting Standards Update 2018-02
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect of accounting change				(30)
Accounting Standards Update 2018-02 | Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect of accounting change				0
Accounting Standards Update 2018-02 | Unrealized Gains (Losses) on Available-for-Sale Investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect of accounting change				0
Accounting Standards Update 2018-02 | Unrealized Gains (Losses) on Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect of accounting change				$ (30)