Annual report pursuant to Section 13 and 15(d)

Derivative Instruments and Hedging Transactions (Realized Gain (Loss)) (Details)

v3.7.0.1
Derivative Instruments and Hedging Transactions (Realized Gain (Loss)) (Details) - USD ($)
$ in Thousands
12 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Derivative [Line Items]    
Gains (losses) on derivative instruments: $ 9,654 $ (5,861)
Futures Commodity And Forwards Contracts And Open Purchase And Sale Commitments    
Derivative [Line Items]    
Unrealized (losses) gains on open future commodity and forward contracts and open sale and purchase commitments, net (17,738) (7,205)
Commodity Contract    
Derivative [Line Items]    
Realized gains (losses) on future commodity contracts, net $ 27,392 $ 1,344