Changes in Operations United Kingdom - Pentalver (Details) £ in Thousands, $ in Thousands			3 Months Ended		6 Months Ended
	May 03, 2017 GBP (£) a employee truck seaport $ / AUD	May 03, 2017 USD ($) a seaport	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($) $ / AUD	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($) $ / AUD	May 03, 2017 USD ($) employee truck $ / AUD	Dec. 31, 2016 USD ($)	Dec. 01, 2016 $ / AUD
Payments to Acquire Businesses, Net of Cash Acquired					$ 102,655	$ 0
Foreign currency exchange rate | $ / AUD	1.29			0.73		0.73	1.29		0.74
Operating Income			$ 101,340	$ 87,194	178,794	$ 144,190
Depreciation and amortization			61,513	$ 50,924	122,287	$ 100,254
Goodwill			$ 1,176,181		1,176,181			$ 1,125,596
Pentalver Transport Limited [Member]
Business Acquisition, Effective Date of Acquisition	May 03, 2017	May 03, 2017
Payments to Acquire Businesses, Gross	£ 97,800	$ 126,200
Payments to Acquire Businesses, Net of Cash Acquired	77,500	100,100
Cash Acquired from Acquisition	£ 20,200	$ 26,100
Number of Major Seaports | seaport	4	4
Number of trucks | truck	150						150
Number of employees | employee	600						600
Revenues					25,900
Operating Income					1,900
Depreciation and amortization					900
Acquisition and integration related costs					2,300
Cash and cash equivalents	£ 20,224						$ 26,117
Accounts receivable	16,847						21,756
Materials and supplies	13,360						17,253
Prepaid expenses and other	3,238						4,182
Property and equipment	22,403						28,931
Goodwill	10,271						13,264
Total Assets	127,343						164,450
Accounts payable and accrued expenses	22,116						28,560
Deferred income tax liabilities, net	6,876						8,880
Deferred items-grants from outside parties	601						776
Net assets	£ 97,750						$ 126,234
Minimum [Member] | Pentalver Transport Limited [Member]
Number of Acres Providing Storage for Loaded and Empty Containers | a	100	100
Maximum [Member] | Pentalver Transport Limited [Member]
Term of contract of operational rights, in years	50 years	50 years
Freightliner [Member]
Number of trucks | truck	200						200
Operational Network Rights [Member] | Pentalver Transport Limited [Member]
Finite-lived Intangible Assets Acquired	£ 41,000	$ 52,947
Other Expense [Member] | Pentalver Transport Limited [Member]
Acquisition and integration related costs					2,200
Labor and Benefits [Member] | Pentalver Transport Limited [Member]
Acquisition and integration related costs					$ 100