Business Combination (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jul. 12, 2016
Acquired Finite-Lived Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents												$ 50,349
trtn_BusinessCombinationsRestrictedCashandCashEquivalents												59,115
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables												75,846
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Equipment												3,052,693
trtn_BusinessCombinationCapitalLeasesNetInvestmentinDirectFinancingLeases												159,885
trtn_BusinessCombinationAssetsHeldforsaleNotPartofDisposal												80,655
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets												32,084
Goodwill	$ 236,665				$ 236,665				$ 236,665	$ 236,665	$ 0	236,665
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable												(63,858)
trtn_BusinessCombinationDerivativeInstruments												(64,206)
trtn_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedLiabilitiesEquipmentPayable												(10,071)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent												(280,610)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt												(3,121,118)
Business Combination, Contingent Consideration, Asset	0				510,186				0	510,186	0	$ 510,186
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	62,884								62,884
Finite-Lived Intangible Assets, Amortization Expense, Year Two	37,184								37,184
Finite-Lived Intangible Assets, Amortization Expense, Year Three	22,632								22,632
Finite-Lived Intangible Assets, Amortization Expense, Year Four	16,652								16,652
Finite-Lived Intangible Assets, Amortization Expense, Rolling Year Five	10,572								10,572
Finite-Lived Intangible Assets, Amortization Expense, Rolling after Year Five	6,643								6,643
Finite-Lived Intangible Assets, Amortization Expense, Remaining Total Balance	156,567								156,567
Operating and Capital Leases Income Statement Lease Revenue	313,856	$ 302,120	$ 281,939	$ 265,602	259,547	$ 247,789	$ 158,333	$ 163,025	1,163,517	828,694	707,839
Business Acquisition, Pro Forma Revenue										1,076,753	1,198,148
Transaction and other costs									9,272	66,916	22,185
Business Acquisition, Pro Forma Net Income (Loss)										36,015	180,638
Net (loss) income	207,160	$ 57,156	$ 45,671	$ 34,611	$ 22,778	$ (51,211)	$ 6,174	$ 8,742	344,598	(13,517)	111,089
AboveMarketLeaseIntangibles [Domain]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	61,451								61,451
Finite-Lived Intangible Assets, Amortization Expense, Year Two	36,426								36,426
Finite-Lived Intangible Assets, Amortization Expense, Year Three	22,632								22,632
Finite-Lived Intangible Assets, Amortization Expense, Year Four	16,652								16,652
Finite-Lived Intangible Assets, Amortization Expense, Rolling Year Five	10,572								10,572
Finite-Lived Intangible Assets, Amortization Expense, Rolling after Year Five	6,643								6,643
Finite-Lived Intangible Assets, Amortization Expense, Remaining Total Balance	154,376								154,376
CustomerIntangibles [Domain]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	1,433								1,433
Finite-Lived Intangible Assets, Amortization Expense, Year Two	758								758
Finite-Lived Intangible Assets, Amortization Expense, Year Three	0								0
Finite-Lived Intangible Assets, Amortization Expense, Year Four	0								0
Finite-Lived Intangible Assets, Amortization Expense, Rolling Year Five	0								0
Finite-Lived Intangible Assets, Amortization Expense, Rolling after Year Five	0								0
Finite-Lived Intangible Assets, Amortization Expense, Remaining Total Balance	$ 2,191								2,191
Merger Specific [Domain]
Acquired Finite-Lived Intangible Assets [Line Items]
Transaction and other costs									9,272	60,437	10,280
TAL [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired												45.00%
Common Stock, Shares, Outstanding												33.4
TCIL [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired												55.00%
Common Stock, Shares, Outstanding												40.8
trtn_BusinessAcquisitionCommonStockShareReceivedRatio												80.00%
Employee Compensation Costs [Member] | Merger Specific [Domain]
Acquired Finite-Lived Intangible Assets [Line Items]
Transaction and other costs									9,271	40,360	3,520
Professional Fees Expense [Member] | Merger Specific [Domain]
Acquired Finite-Lived Intangible Assets [Line Items]
Transaction and other costs									0	14,295	2,841
Legal Expense [Member] | Merger Specific [Domain]
Acquired Finite-Lived Intangible Assets [Line Items]
Transaction and other costs									10	3,370	3,919
Other Expense [Member] | Merger Specific [Domain]
Acquired Finite-Lived Intangible Assets [Line Items]
Transaction and other costs									$ (9)	$ 2,412	$ 0
Common Stock [Member] | TAL [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Share Price												$ 15.28
Other Intangible Assets [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life									1 year 11 months
Other Intangible Assets [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life									1 year 6 months