Insurance Matters (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2012	Sep. 30, 2011
Insurance Matters [Abstract]
Minimum insurance deductible per incident	$ 5.0	$ 5.0
Maximum insurance deductible per incident	60.0	60.0
Coverage by certain producers for each of the Independence Hub and Marco Polo platforms	350.0	350.0
Proceeds from property damage insurance recoveries	$ 2.3	$ 30.0	$ 0

The cash inflow from the amounts received by the insured under the terms of an insurance contract settlement. This element pertains only to insurance proceeds related to investments, for example fixed assets. It excludes insurance settlements classified as operating cash flows.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3179-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 22

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_ProceedsFromInsuranceSettlementInvestingActivities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration