Other Long-Term Liabilities - Components of Other Long-Term Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Other Liabilities Noncurrent [Abstract]
Assumed gathering, processing and transportation contracts	$ 482
Pension and post retirement benefit obligations	225	$ 243
Restructuring and transaction costs	130	137
Estimated future obligation under a performance guarantee	128
Commodity derivatives	122	5
Other	182	166
Total other long-term liabilities	$ 1,269	$ 551