Asset Retirement Obligations (Details Textual) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
AssetRetirementObligationDisclosureAbstract
Asset Retirement Obligations Significant Changes Due To Changes In The Timing And Method Of Abandonment	$ 13	$ 39
Asset Retirement Obligation Annual Funding	16.7
Asset Retirement Obligations Significant Changes Annual Review Process		$ 35

Amount of the significant increases or decreases in the carrying amount of the asset retirement obligation during the period, such as changes in significant assumptions used to calculate the carrying amount of the asset retirement obligation.

No definition available.

Name:	tgplc_AssetRetirementObligationsSignificantChangesAmount
Namespace Prefix:	tgplc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant