Derivatives - Gross Notional Values (Details) bbl in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($) bbl
Long | Commodity contracts
Derivative instruments, at their respective fair value positions
Notional value of commodity contracts (in barrels) | bbl	57.0
Long | Foreign currency contracts | USD
Derivative instruments, at their respective fair value positions
Notional amount of foreign currency contracts | $	$ 414.0
Short | Commodity contracts
Derivative instruments, at their respective fair value positions
Notional value of commodity contracts (in barrels) | bbl	60.9
Short | Foreign currency contracts | USD
Derivative instruments, at their respective fair value positions
Notional amount of foreign currency contracts | $	$ 280.6