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Equity Method Investments - Narrative (Details) - USD ($)
$ in Thousands
1 Months Ended 12 Months Ended
Nov. 30, 2019
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Feb. 10, 2020
Feb. 28, 2014
Apr. 30, 2012
Schedule of Equity Method Investments [Line Items]              
Reclassification of accumulated losses   $ 9,400 $ 0 $ 0      
Net proceeds from sale of investment   249,463 0 0      
Transcontinental Gas Pipe Line Company LLC              
Schedule of Equity Method Investments [Line Items]              
Entity's equity interest in construction agreement (as a percent)           61.00%  
Constitution Pipeline Company, LLC              
Schedule of Equity Method Investments [Line Items]              
Ownership interest             25.00%
Equity method investment OTTI       95,900      
Reclassification of accumulated losses   9,400 0 0      
Meade Pipeline Co LLC              
Schedule of Equity Method Investments [Line Items]              
Ownership interest           20.00%  
Reclassification of accumulated losses   $ 0 $ 0 $ 0      
Entity's equity interest in construction agreement (as a percent)           39.00%  
Net proceeds from sale of investment $ 249,500            
Gain on sale of investment 75,800            
Escrow related to certain contingencies $ 13,600            
Subsequent Event | Constitution Pipeline Company, LLC              
Schedule of Equity Method Investments [Line Items]              
Ownership interest         25.00%