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Newly-Formed Joint Ventures and Acquisitions - Additional Information Acquisitions (Details) - Permian Acquisition [Member] - USD ($)
3 Months Ended
May 30, 2017
Mar. 01, 2017
Mar. 31, 2017
Mar. 31, 2018
Dec. 31, 2017
Business Acquisition [Line Items]          
Business Acquisition, Percentage of Voting Interests Acquired   100.00%      
Cash payments related to acquisition   $ 484,100,000      
Acquired debt and all other assumed liabilities included in purchase consideration $ 90,000,000   $ 90,000,000    
Additional cash that may be paid based on potential earn-out payment       $ 373,000,000 $ 317,000,000
Acquisition-related expenses     $ 5,100,000    
Maximum [Member]          
Business Acquisition [Line Items]          
Additional cash that may be paid based on potential earn-out payment   $ 935,000,000   $ 935,000,000