Derivative Financial Instruments Foreign Currency Exchange Rate Risk (Details) £ in Thousands, AUD in Millions			3 Months Ended				6 Months Ended
	Feb. 25, 2015 GBP (£)	Feb. 25, 2015 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 GBP (£)	Mar. 31, 2015 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 GBP (£)	Jun. 30, 2016 USD ($)	Mar. 25, 2015 GBP (£)	Mar. 25, 2015 USD ($)	Mar. 23, 2015 GBP (£)	Feb. 25, 2015 AUD	Feb. 25, 2015 GBP (£)	Feb. 25, 2015 USD ($)
Derivative [Line Items]
Foreign subsidiaries third-party debt denominated in local currencies										$ 498,700,000
Cash received on settlement of forward currency forward purchase contracts | £													£ 391,800
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments			$ 0	$ 0			$ 0	$ (18,686,000)
Intercompany loan, amount											£ 120,000	$ 181,000,000
Accrued Liabilities									£ 9,500	$ 12,700,000
Foreign currency forward purchase contract 1 [Member]
Derivative [Line Items]
Notional amount															£ 307,100	$ 475,000,000
Foreign currency forward purchase contract 2 [Member]
Derivative [Line Items]
Notional amount														AUD 163.8	£ 84,700
Foreign Exchange Forward [Member]
Derivative [Line Items]
Gain/(loss) reclassified from accumulated other comprehensive income/(loss) into earnings due to ineffectiveness			0	$ 0			0	0
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion							266,000
Existing net gains/losses expected to be realized within the next 12 months							800,000
Intercompany Loan [Member]
Derivative [Line Items]
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion			14,500,000				18,900,000
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net			8,700,000				$ 11,400,000
Forward Contracts [Member]
Derivative [Line Items]
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments								$ 18,700,000
British Pound Foreign Currency Forward Contract 1 [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 Contract 2 [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 Contract 3 [Member]
Derivative [Line Items]
Notional amount | £									£ 2,035
Effective Date							Jun. 30, 2015
Settlement Date							Mar. 31, 2020
Exchange Rate									1.57	1.57
British Pound Foreign Currency Forward Contract 4 [Member]
Derivative [Line Items]
Notional amount | £									£ 1,846
Effective Date							Sep. 30, 2015
Settlement Date							Mar. 31, 2020
Exchange Rate									1.51	1.51
British Pound Foreign Currency Forward Contract 5 [Member]
Derivative [Line Items]
Notional amount | £									£ 1,873
Effective Date							Dec. 31, 2015
Settlement Date							Mar. 31, 2020
Exchange Rate									1.48	1.48
British Pound Foreign Currency Forward Contract 6 [Member]
Derivative [Line Items]
Notional amount | £									£ 1,881
Effective Date							Mar. 31, 2016
Settlement Date							Mar. 31, 2020
Exchange Rate									1.45	1.45
British Pound Foreign Currency Forward Contract 7 [Member]
Derivative [Line Items]
Notional amount | £									£ 1,909
Effective Date							Jun. 30, 2016
Settlement Date							Mar. 31, 2020
Exchange Rate									1.35	1.35
Freightliner [Member]
Derivative [Line Items]
Cash consideration paid to acquire business	£ 490,000	$ 755,000,000
Cash purchase price					£ 492,083	$ 733,006,000
Intercompany Loan [Member]
Derivative [Line Items]
Foreign Currency Transaction Gain (Loss), before Tax			(14,540,000)				$ (18,926,000)
Foreign Currency Transaction Gain (Loss), Net of Tax			$ (8,724,000)				$ (11,356,000)