Summary of Accounting Policies - Notes and Accounts Receivable and Allowance for Doubtful Accounts (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Allowance for doubtful accounts on short-term and long-term accounts receivable	$ 28,000,000	$ 17,000,000
Allowance for doubtful accounts on short-term and long-term notes receivable	$ 0	$ 0