Derivative Instruments - Gross Notional Values (Details) bbl in Millions, $ in Millions	12 Months Ended
Dec. 31, 2017 USD ($) bbl
Buy / Long \| Commodity contracts
Derivative [Line Items]
Notional value of commodity contracts \| bbl	66.5
Buy / Long \| Foreign currency contracts \| U.S. dollar
Derivative [Line Items]
Notional amount of foreign currency contracts \| $	$ 485.5
Sell / Short \| Commodity contracts
Derivative [Line Items]
Notional value of commodity contracts \| bbl	75.9
Sell / Short \| Foreign currency contracts \| U.S. dollar
Derivative [Line Items]
Notional amount of foreign currency contracts \| $	$ 255.8

Nominal or face amount used to calculate payments on the derivative asset.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5579245-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5580258-113959

Name:	us-gaap_DerivativeAssetNotionalAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant