Acquisitions and Divestitures - Liabilities Assumed from Acquisition of Businesses (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Combinations [Abstract]
Fair value of assets acquired	$ 219	$ 110	$ 857
Cash and stock consideration (net of cash acquired)	201	91	803
Liabilities assumed	$ 18	$ 19	$ 54

Value of investments transferred to the entity's investments in noncash transactions.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration