Goodwill and Intangible Assets - Intangible Assets (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 5,010		$ 5,010		$ 4,816
Accumulated Amortization	(4,151)		(4,151)		(3,922)
Net Carrying Amount	859		859		894
Amortization expense	118	$ 156	$ 229	$ 312
Acquired users
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Remaining Useful Lives (in years)			1 year 3 months 18 days
Gross Carrying Amount	2,056		$ 2,056		2,056
Accumulated Amortization	(1,694)		(1,694)		(1,550)
Net Carrying Amount	362		$ 362		506
Acquired technology
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Remaining Useful Lives (in years)			3 years 1 month 6 days
Gross Carrying Amount	1,288		$ 1,288		1,158
Accumulated Amortization	(1,032)		(1,032)		(986)
Net Carrying Amount	256		$ 256		172
Acquired patents
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Remaining Useful Lives (in years)			4 years 3 months 18 days
Gross Carrying Amount	805		$ 805		805
Accumulated Amortization	(652)		(652)		(625)
Net Carrying Amount	153		$ 153		180
Trade names
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Remaining Useful Lives (in years)			1 year 8 months 12 days
Gross Carrying Amount	638		$ 638		635
Accumulated Amortization	(614)		(614)		(604)
Net Carrying Amount	24		$ 24		31
Other
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Remaining Useful Lives (in years)			3 years 8 months 12 days
Gross Carrying Amount	223		$ 223		162
Accumulated Amortization	(159)		(159)		(157)
Net Carrying Amount	$ 64		$ 64		$ 5