Acquisitions - Purchase Price Allocation (Details) - USD ($) $ in Millions	Mar. 19, 2021	Feb. 13, 2020	Jun. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Business Acquisition [Line Items]
Goodwill			$ 4,590	$ 4,556	$ 3,722
Cortera
Business Acquisition [Line Items]
Current assets	$ 7
Total intangible assets	57
Goodwill	95
Other assets	2
Liabilities:
Accounts payable and accrued liabilities	(1)
Deferred revenue	(4)
Deferred tax liabilities	(15)
Other liabilities	(2)
Total liabilities	(22)
Net assets acquired	$ 139
Acquired finite-lived intangible asset, useful life	11 years
Cortera | Database
Business Acquisition [Line Items]
Total intangible assets	$ 38
Liabilities:
Finite-lived intangible asset, useful life	10 years
Cortera | Customer relationships
Business Acquisition [Line Items]
Total intangible assets	$ 9
Liabilities:
Finite-lived intangible asset, useful life	18 years
Cortera | Product technology
Business Acquisition [Line Items]
Total intangible assets	$ 9
Liabilities:
Finite-lived intangible asset, useful life	8 years
Cortera | Trade names
Business Acquisition [Line Items]
Total intangible assets	$ 1
Liabilities:
Finite-lived intangible asset, useful life	5 years
Regulatory Data Corporation
Business Acquisition [Line Items]
Current assets		$ 24
Total intangible assets		280
Goodwill		494
Other assets		2
Liabilities:
Accounts payable and accrued liabilities		(5)
Deferred revenue		(20)
Deferred tax liabilities		(71)
Other liabilities		(2)
Total liabilities		(98)
Net assets acquired		$ 702
Acquired finite-lived intangible asset, useful life		19 years
Regulatory Data Corporation | Database
Business Acquisition [Line Items]
Total intangible assets		$ 86
Liabilities:
Finite-lived intangible asset, useful life		10 years
Regulatory Data Corporation | Customer relationships
Business Acquisition [Line Items]
Total intangible assets		$ 174
Liabilities:
Finite-lived intangible asset, useful life		25 years
Regulatory Data Corporation | Product technology
Business Acquisition [Line Items]
Total intangible assets		$ 17
Liabilities:
Finite-lived intangible asset, useful life		4 years
Regulatory Data Corporation | Trade names
Business Acquisition [Line Items]
Total intangible assets		$ 3
Liabilities:
Finite-lived intangible asset, useful life		3 years