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Transactions with Affiliates (Details) (USD $)
3 Months Ended 1 Months Ended
Mar. 31, 2015
employee
Mar. 31, 2014
Apr. 30, 2015
Dec. 31, 2014
Related Party Transaction [Line Items]        
Advances to affiliate $ 205,249,000us-gaap_NotesReceivableRelatedPartiesCurrent     $ 306,910,000us-gaap_NotesReceivableRelatedPartiesCurrent
Related party transaction, rate 0.01%us-gaap_RelatedPartyTransactionRate      
Operating revenues, related party 1,200,000us-gaap_RevenueFromRelatedParties 1,300,000us-gaap_RevenueFromRelatedParties    
Cost of natural gas sales, related party 2,500,000us-gaap_RelatedPartyTransactionPurchasesFromRelatedParty 3,400,000us-gaap_RelatedPartyTransactionPurchasesFromRelatedParty    
Entity number of employees 0dei_EntityNumberOfEmployees      
Expenses, related party 81,000,000us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty 75,200,000us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty    
Cash distributions to parent 123,000,000us-gaap_PaymentsOfDistributionsToAffiliates 112,000,000us-gaap_PaymentsOfDistributionsToAffiliates    
Cash contributions to parent 158,000,000us-gaap_ProceedsFromContributionsFromParent 54,000,000us-gaap_ProceedsFromContributionsFromParent    
Affiliated Entity [Member]        
Related Party Transaction [Line Items]        
Expenses, related party (1,200,000)us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_AffiliatedEntityMember
(1,300,000)us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_AffiliatedEntityMember
   
Williams Partners L.P. [Member]        
Related Party Transaction [Line Items]        
Advances to affiliate 205,200,000us-gaap_NotesReceivableRelatedPartiesCurrent
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= tgpl_WilliamsPartnersL.P.Member
    306,900,000us-gaap_NotesReceivableRelatedPartiesCurrent
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= tgpl_WilliamsPartnersL.P.Member
Williams Field Services Group, LLC [Member]        
Related Party Transaction [Line Items]        
Pre-payments for capital projects   4,200,000us-gaap_ContributionsInAidOfConstruction
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= tgpl_WilliamsFieldServicesGroupLLCMember
   
Subsequent Event [Member]        
Related Party Transaction [Line Items]        
Cash distributions to parent     110,000,000us-gaap_PaymentsOfDistributionsToAffiliates
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
 
Cash contributions to parent     $ 154,000,000us-gaap_ProceedsFromContributionsFromParent
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember