Supplemental Financial Statement Information (Components of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Components of AOCI, net of tax
Beginning Balance	$ 201,442	$ 177,628
Other comprehensive income (loss) before reclassifications	1,803	1,509
Amounts excluded from the assessment of hedge effectiveness recorded in AOCI	(20)	(13)
Amounts reclassified from AOCI	(505)	(356)
Other comprehensive income (loss)	1,278	1,140
Ending Balance	212,920	194,969
Cumulative Effect, Period of Adoption, Adjustment
Components of AOCI, net of tax
Beginning Balance		(34)
Total
Components of AOCI, net of tax
Beginning Balance	(1,232)	(2,306)
Ending Balance	46	(1,196)
Total | Cumulative Effect, Period of Adoption, Adjustment
Components of AOCI, net of tax
Beginning Balance		(30)
Foreign Currency Translation Adjustments
Components of AOCI, net of tax
Beginning Balance	(2,003)	(1,884)
Other comprehensive income (loss) before reclassifications	193	(326)
Amounts excluded from the assessment of hedge effectiveness recorded in AOCI	0	0
Amounts reclassified from AOCI	0	0
Other comprehensive income (loss)	193	(326)
Ending Balance	(1,810)	(2,210)
Foreign Currency Translation Adjustments | Cumulative Effect, Period of Adoption, Adjustment
Components of AOCI, net of tax
Beginning Balance		0
Unrealized Gains (Losses) on Available-for-Sale Investments
Components of AOCI, net of tax
Beginning Balance	812	(688)
Other comprehensive income (loss) before reclassifications	1,346	1,613
Amounts excluded from the assessment of hedge effectiveness recorded in AOCI	0	0
Amounts reclassified from AOCI	(391)	(107)
Other comprehensive income (loss)	955	1,506
Ending Balance	1,767	818
Unrealized Gains (Losses) on Available-for-Sale Investments | Cumulative Effect, Period of Adoption, Adjustment
Components of AOCI, net of tax
Beginning Balance		0
Unrealized Gains (Losses) on Cash Flow Hedges
Components of AOCI, net of tax
Beginning Balance	(41)	266
Other comprehensive income (loss) before reclassifications	264	222
Amounts excluded from the assessment of hedge effectiveness recorded in AOCI	(20)	(13)
Amounts reclassified from AOCI	(114)	(249)
Other comprehensive income (loss)	130	(40)
Ending Balance	$ 89	196
Unrealized Gains (Losses) on Cash Flow Hedges | Cumulative Effect, Period of Adoption, Adjustment
Components of AOCI, net of tax
Beginning Balance		$ (30)