Goodwill (Schedule Of Changes By Segment To The Carrying Amount Of Goodwill) (Details) $ in Millions	Dec. 31, 2015 USD ($)
Refining Segment
Goodwill [Line Items]
Goodwill, Gross	$ 2,042.8
Cheyenne [Member]
Goodwill [Line Items]
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount	8.00%
Variable Interest Entity, Primary Beneficiary [Member]
Goodwill [Line Items]
Goodwill, Gross	$ 289.0

Amount before accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a,h)
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Name:	us-gaap_GoodwillGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant