Nature of Operations and Basis of Presentation - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($) Segment	Dec. 31, 2019 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reportable segments | Segment	4
Restricted cash	$ 10	$ 15
Contract asset	38	28
Unearned revenue	812
Revenue expected to be recognized as of period end	2,000
Capitalized contract costs	$ 112	$ 115
Amortization period of capitalized contract cost	5 years