Derivative Financial Instruments Foreign Currency Exchange Rate Risk (Details) £ in Thousands, AUD in Millions					3 Months Ended			9 Months Ended
	Feb. 25, 2015 GBP (£)	Feb. 25, 2015 USD ($)	May. 23, 2014 AUD	May. 23, 2014 USD ($)	Sep. 30, 2015 USD ($)	Mar. 31, 2015 GBP (£)	Mar. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 GBP (£)	Sep. 30, 2015 USD ($)	Mar. 23, 2015 USD ($)	Feb. 25, 2015 AUD	Feb. 25, 2015 GBP (£)	Feb. 25, 2015 USD ($)	Dec. 03, 2012 AUD	Dec. 03, 2012 USD ($)
Derivative [Line Items]
Foreign subsidiaries third-party debt denominated in local currencies											$ 483,300,000
Cash received on settlement of forward currency forward purchase contracts												$ 391,800,000
Net expense realized or recognized on cross-currency swap agreement								$ (18,686,000)	$ (1,270,000)
Intercompany loan, amount										£ 120,000	$ 181,000,000
Foreign Exchange Forward [Member]
Derivative [Line Items]
Gain/(loss) reclassified from accumulated other comprehensive income/(loss) into earnings due to ineffectiveness					$ 0			$ 0
British Pound foreign currency forward purchase contract 1 [Member]
Derivative [Line Items]
Notional amount														£ 307,100	$ 475,000,000
British Pound foreign currency forward purchase contract 2 [Member]
Derivative [Line Items]
Notional amount													AUD 163.8	£ 84,700
British pound foreign currency forward purchase contract 3 [Member]
Derivative [Line Items]
Notional amount | £										£ 60,000
Effective Date								Mar. 25, 2015
Settlement Date								Mar. 31, 2020
Exchange Rate										1.50	1.50
British Pound foreign currency forward purchase contract 4 [Member]
Derivative [Line Items]
Notional amount | £										£ 60,000
Effective Date								Mar. 25, 2015
Settlement Date								Mar. 31, 2020
Exchange Rate										1.51	1.51
British Pound foreign currency forward purchase contract 5 [Member]
Derivative [Line Items]
Notional amount | £										£ 2,035
Derivative, Amount of Hedged Item										£ 3,900	$ 5,900,000
Gain/(loss) reclassified from accumulated other comprehensive income/(loss) into earnings due to ineffectiveness								$ 0
Effective Date								Jun. 30, 2015
Settlement Date								Mar. 31, 2020
Exchange Rate										1.57	1.57
British Pound foreign currency forward purchase contract 6 [Member]
Derivative [Line Items]
Notional amount | £										£ 1,846
Effective Date								Sep. 30, 2015
Settlement Date								Mar. 31, 2020
Exchange Rate										1.51	1.51
Cross-currency swap agreements [Member]
Derivative [Line Items]
Notional amount																AUD 105.0	$ 109,600,000
Payments in connection with termination of cross-currency swap | AUD			AUD 105.0
Proceeds in connection with termination of cross-currency swap				$ 108,900,000
Freightliner [Member]
Derivative [Line Items]
Cash purchase price						£ 492,083	$ 733,006,000
Scenario, Plan [Member] | Freightliner [Member]
Derivative [Line Items]
Estimated Payments to Acquire Businesses, Gross	£ 490,000	$ 755,000,000
Not Designated as Hedging Instrument [Member] | Interest expense [Member] | Cross-currency swap agreements [Member]
Derivative [Line Items]
Net expense realized or recognized on cross-currency swap agreement								$ 0	(1,184,000)
Not Designated as Hedging Instrument [Member] | Other (loss)/income, net | Cross-currency swap agreements [Member]
Derivative [Line Items]
Net expense realized or recognized on cross-currency swap agreement								$ 0	$ (86,000)