XML 64 R43.htm IDEA: XBRL DOCUMENT v3.19.3
Revenues and Accounts Receivable - Narrative (Details) - USD ($)
$ in Millions
Sep. 30, 2019
Dec. 31, 2018
Minimum Volume Commitments [Line Items]    
Contract liability $ 193 $ 338
Minimum Volume Commitments    
Minimum Volume Commitments [Line Items]    
Counterparty deficiencies 50 62
Contract liability 30 40
Counterparty deficiencies unbilled and uncollected $ 20 $ 22