Accounting Policies - Narrative (Details)	1 Months Ended	3 Months Ended								12 Months Ended
	Apr. 30, 2018 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) units Segment	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jan. 01, 2018 USD ($)
Property, Plant and Equipment [Line Items]
Number of reportable segments | Segment										4
Consideration paid for acquisition, net of cash acquired										$ 91,000,000	$ 401,000,000
Retained earnings (accumulated deficit)		$ 12,205,000,000				$ 11,284,000,000				12,205,000,000	11,284,000,000
Total revenue		(1,735,000,000)	$ (1,689,000,000)	$ (1,704,000,000)	$ (1,571,000,000)	(1,536,000,000)	$ (1,546,000,000)	$ (1,609,000,000)	$ (1,567,000,000)	(6,699,000,000)	(6,258,000,000)	$ (6,063,000,000)
Contract assets		28,000,000				26,000,000				28,000,000	26,000,000
Remaining performance obligations		1,900,000,000								$ 1,900,000,000
Revenue recognized next year (as a percent)										50.00%
Revenue recognized within two years (as a percent)										75.00%
Market value of cash and cash equivalents		2,866,000,000				1,917,000,000				$ 2,866,000,000	1,917,000,000
Gross deferred technology costs		212,000,000				205,000,000				212,000,000	205,000,000
Accumulated amortization of deferred technology costs		129,000,000				105,000,000				129,000,000	105,000,000
Fair value of our long-term debt borrowings		3,900,000,000				3,800,000,000				$ 3,900,000,000	3,800,000,000
Number of reporting units | units										4
Cost of advertisement										$ 34,000,000	33,000,000	33,000,000
Undistributed accumulated earnings of foreign subsidiary		3,200,000,000								3,200,000,000
Undistributed accumulated earnings of foreign subsidiary to be indefinitely reinvested		776,000,000								776,000,000
Goodwill impairment										0	0	0
Indefinite-lived intangible asset impairment										$ 0	0	0
Minimum | Software and Software Development Costs
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life										3 years
Minimum | Building Improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life										15 years
Minimum | Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life										2 years
Maximum | Software and Software Development Costs
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life										7 years
Maximum | Building Improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life										40 years
Maximum | Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life										10 years
Kensho Technologies
Property, Plant and Equipment [Line Items]
Consideration paid for acquisition, net of cash acquired	$ 550,000,000
Restricted cash		15,000,000				32,000,000				$ 15,000,000	32,000,000
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Property, Plant and Equipment [Line Items]
Retained earnings (accumulated deficit)													$ 35,000,000
Unearned revenue recognized										1,700,000,000
Capitalized contract costs		$ 115,000,000				$ 101,000,000				115,000,000	101,000,000
Non-transaction
Property, Plant and Equipment [Line Items]
Total revenue										(1,401,000,000)	(1,408,000,000)	(1,363,000,000)
Intersegment Elimination
Property, Plant and Equipment [Line Items]
Total revenue										128,000,000	125,000,000	110,000,000
Intersegment Elimination | Non-transaction
Property, Plant and Equipment [Line Items]
Total revenue										$ 128,000,000	$ 125,000,000	$ 110,000,000