Acquisitions and Dispositions of Businesses - Schedule of Net Assets Acquired (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Assets acquired
Goodwill	$ 8,666	$ 8,165	$ 8,171
2019 and 2020 acquisitions
Consideration transferred
Cash	385
Deferred, contingent, and other consideration	34
Aggregate consideration transferred	419
Assets acquired
Cash and cash equivalents	17
Receivables, net	19
Goodwill	314
Intangible assets, net	83
Current assets	16
Non-current assets	12
Total assets acquired	461
Liabilities assumed
Current liabilities	27
Non-current liabilities	15
Total liabilities assumed	42
Net assets acquired	$ 419