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Summary of Significant Accounting Policies (details) - Equity Method Investment (JMalucelli - Brazilian joint venture [Member])
Dec. 31, 2014
JMalucelli - Brazilian joint venture [Member]
 
Equity method investment  
Percent of common stock owned 49.50%us-gaap_EquityMethodInvestmentOwnershipPercentage
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= trv_JMalucelliMember