Annual report pursuant to Section 13 and 15(d)

Fair Value (Details)

v3.6.0.2
Fair Value (Details)
12 Months Ended
Dec. 31, 2016
USD ($)
Bcf / d
Dec. 31, 2015
USD ($)
Bcf / d
Dec. 31, 2014
USD ($)
Mar. 30, 2016
USD ($)
Instrument
Dec. 20, 2012
USD ($)
Schedule of Equity Method Investments [Line Items]          
Unrealized gain on other equity securities $ 43,000 $ 365,000 $ 5,000    
Lightfoot Capital Partners LP [Member]          
Schedule of Equity Method Investments [Line Items]          
Equity interest percentage 6.60% 1.50%      
Minimum [Member] | Lightfoot Capital Partners LP [Member]          
Schedule of Equity Method Investments [Line Items]          
Discount percentage for lack of marketability   11.80%      
Discount rate percentage 14.50% 14.00%      
Maximum [Member] | Lightfoot Capital Partners LP [Member]          
Schedule of Equity Method Investments [Line Items]          
Discount percentage for lack of marketability   15.20%      
Discount rate percentage 16.50% 16.00%      
Cash Flow Hedging [Member]          
Schedule of Equity Method Investments [Line Items]          
Number of instruments terminated | Instrument       1  
Notional amount       $ 26,300,000  
Pinedale Credit Facilities [Member] | Key Bank [Member]          
Schedule of Equity Method Investments [Line Items]          
Maximum borrowing capacity         $ 70,000,000
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]          
Receiving and regasification terminal, volume per day (bcf/d) | Bcf / d 1,500,000,000        
Limited partner interest 40.00%