Amount of unrealized gain (loss) related to the increase or decrease in fair value of interest rate derivatives designated as cash flow hedging instruments, which was recorded in accumulated other comprehensive income to the extent that the cash flow hedge was determined to be effective.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 46

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5624171-113959

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Derivative Instruments (Details Textual) (USD $) In Millions, unless otherwise specified		3 Months Ended
	Mar. 31, 2012	Mar. 31, 2012 Interest Rate Locks, 2005 to 2006 [Member]	Mar. 31, 2012 Interest Rate Locks, 2006 to 2007 [Member]	Mar. 31, 2012 Interest Rate Swap TRIP Rail Master Funding Secured Railcar Equipment Notes [Member]	Jul. 31, 2011 Interest Rate Swap TRIP Rail Master Funding Secured Railcar Equipment Notes [Member]
Derivative Instruments (Textual) [Abstract]
Interest rate swap, notional amount		$ 200.0	$ 370.0	$ 86.7	$ 94.1
Interest rate swaps being accounted for as cash flow hedges		4.5	24.5
Derivative Instruments (Additional Textual) [Abstract]
Additional interest expense expected to be recognized	6.0
Short term instruments with quarterly maturities	$ 0