Nature of Operations and Summary of Significant Accounting Policies - Contract Assets, Receivables, and Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Revenues	$ 3,071	$ 1,268	$ 8,625	$ 3,814
Trade receivables before allowance for credit loss	2,019		$ 2,019		$ 950
Percentage of outstanding receivables less than 90 days			91.00%
Trade receivables (net of allowances of $44 and $21, respectively)	$ 1,975		$ 1,975		$ 929