The Company and Summary of Significant Accounting Policies (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2019
Accounting Policies [Abstract]
Allowance for doubtful accounts and authorized credits	$ 106,000,000				$ 102,000,000				$ 106,000,000	$ 102,000,000
Deferred revenue recognized during period									96,000,000	88,000,000
Property, Plant and Equipment [Line Items]
Capitalized software development costs									147,000,000	140,000,000
Amortization of previously capitalized software									160,000,000	156,000,000	$ 149,000,000
Advertising expense									1,400,000,000	1,300,000,000	1,200,000,000
Impairment of long-lived assets									0	0	0
New Accounting Pronouncement, Early Adoption [Line Items]
Net revenues	2,877,000,000	$ 2,649,000,000	$ 2,640,000,000	$ 2,580,000,000	2,707,000,000	$ 2,498,000,000	$ 2,419,000,000	$ 2,303,000,000	10,746,000,000	9,927,000,000	9,298,000,000
Cost of net revenues									2,382,000,000	2,221,000,000	2,004,000,000
Sales and marketing									3,391,000,000	2,878,000,000	2,691,000,000
Net income (loss)	$ 760,000,000	$ 721,000,000	$ 642,000,000	$ 407,000,000	$ (2,601,000,000)	$ 520,000,000	$ 29,000,000	$ 1,035,000,000	$ 2,530,000,000	$ (1,017,000,000)	$ 7,266,000,000
Net income (loss) per share - basic (in usd per share)	$ 0.81	$ 0.74	$ 0.64	$ 0.40	$ (2.51)	$ 0.49	$ 0.03	$ 0.96	$ 2.58	$ (0.95)	$ 6.41
Net income (loss) per share - diluted (in usd per share)	$ 0.80	$ 0.73	$ 0.64	$ 0.40	$ (2.51)	$ 0.48	$ 0.03	$ 0.94	$ 2.55	$ (0.95)	$ 6.35
As Reported
New Accounting Pronouncement, Early Adoption [Line Items]
Net revenues										$ 9,567,000,000	$ 8,979,000,000
Cost of net revenues										2,222,000,000	2,007,000,000
Sales and marketing										2,515,000,000	2,368,000,000
Net income (loss)										$ (1,016,000,000)	$ 7,266,000,000
Net income (loss) per share - basic (in usd per share)										$ (0.95)	$ 6.41
Net income (loss) per share - diluted (in usd per share)										$ (0.95)	$ 6.35
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
New Accounting Pronouncement, Early Adoption [Line Items]
Increase in deferred revenue					$ 20,000,000					$ 20,000,000	$ 19,000,000
Sales and marketing										$ 363,000,000	$ 323,000,000
Building and Building Improvements
Property, Plant and Equipment [Line Items]
Estimated useful lives									30 years
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Estimated useful lives									5 years
Furniture and Fixtures and Vehicles
Property, Plant and Equipment [Line Items]
Estimated useful lives									3 years
Minimum
Property, Plant and Equipment [Line Items]
Finite-lived intangible asset, useful life									1 year
Minimum | Internal Use Software And Website Development
Property, Plant and Equipment [Line Items]
Estimated useful lives									1 year
Minimum | Computer Equipment
Property, Plant and Equipment [Line Items]
Estimated useful lives									1 year
Minimum | Scenario, Forecast
New Accounting Pronouncement, Early Adoption [Line Items]
ROU asset												$ 700,000,000
Lease liability												700,000,000
Maximum
Property, Plant and Equipment [Line Items]
Finite-lived intangible asset, useful life									5 years
Maximum | Internal Use Software And Website Development
Property, Plant and Equipment [Line Items]
Estimated useful lives									5 years
Maximum | Computer Equipment
Property, Plant and Equipment [Line Items]
Estimated useful lives									3 years
Maximum | Scenario, Forecast
New Accounting Pronouncement, Early Adoption [Line Items]
ROU asset												800,000,000
Lease liability												$ 800,000,000