Quarterly report pursuant to Section 13 or 15(d)

Fair Value - Additional Information (Details)

v3.8.0.1
Fair Value - Additional Information (Details)
$ / shares in Units, $ in Millions
9 Months Ended 12 Months Ended
Feb. 07, 2018
USD ($)
$ / shares
Sep. 30, 2017
Bcf / d
Dec. 31, 2016
Mar. 30, 2016
USD ($)
Instrument
Lightfoot Capital Partners LP [Member]        
Schedule of Equity Method Investments [Line Items]        
Equity interest percentage   6.60% 6.60%  
Lightfoot GP [Member]        
Schedule of Equity Method Investments [Line Items]        
Equity interest percentage   1.50% 1.50%  
Minimum [Member] | Lightfoot Capital Partners LP [Member]        
Schedule of Equity Method Investments [Line Items]        
Discount rate percentage     15.30%  
Maximum [Member] | Lightfoot Capital Partners LP [Member]        
Schedule of Equity Method Investments [Line Items]        
Discount rate percentage     17.30%  
Cash Flow Hedging [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of instruments terminated | Instrument       1
Notional amount       $ 26.3
Lightfoot Capital Partners LP [Member]        
Schedule of Equity Method Investments [Line Items]        
Receiving and regasification terminal, volume per day (bcf/d) | Bcf / d   1.5    
Lightfoot Capital Partners LP [Member] | Arc Logistics Partners LP [Member]        
Schedule of Equity Method Investments [Line Items]        
Limited partner interest   40.00%    
Forecast [Member] | Lightfoot Capital Partners LP [Member] | Arc Logistics Partners LP [Member]        
Schedule of Equity Method Investments [Line Items]        
Sale of interest, price per share (in dollars per share) | $ / shares $ 14.50      
Forecast [Member] | Lightfoot Capital Partners LP [Member] | Gulf LNG [Member]        
Schedule of Equity Method Investments [Line Items]        
Proceeds from sale of interest $ 63.6      
Forecast [Member] | General Partner [Member] | Lightfoot Capital Partners LP [Member]        
Schedule of Equity Method Investments [Line Items]        
Proceeds from sale of interest $ 94.5