Quarterly report pursuant to Section 13 or 15(d)

Derivative Instruments and Hedging Transactions (Outstanding Commitments) (Details)

v3.8.0.1
Derivative Instruments and Hedging Transactions (Outstanding Commitments) (Details) - USD ($)
$ in Thousands
Sep. 30, 2017
Jun. 30, 2017
Derivative [Line Items]    
Purchase commitments $ 567,595 $ 587,687
Sales commitments (97,564) (121,602)
Margin sales commitments (7,206) (7,936)
Open derivative contracts 627,680 595,681
Forward contracts    
Derivative [Line Items]    
Open derivative contracts 465,861 462,231
Future contracts    
Derivative [Line Items]    
Open derivative contracts $ 161,819 $ 133,450