Change in the Carrying Amount of Goodwill by Segment (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014
Goodwill [Line Items]
Balance at December 31, 2013	$ 786,433
Adjustment to preliminary purchase allocation	(4,042)
Acquisitions	100,544
Foreign currency impact	(18,475)
Balance at September 30, 2014	864,460
Freight Segment
Goodwill [Line Items]
Balance at December 31, 2013	509,664
Adjustment to preliminary purchase allocation	(2,488)
Acquisitions	18,168
Foreign currency impact	(3,236)
Balance at September 30, 2014	522,108
Transit Segment
Goodwill [Line Items]
Balance at December 31, 2013	276,769
Adjustment to preliminary purchase allocation	(1,554)
Acquisitions	82,376
Foreign currency impact	(15,239)
Balance at September 30, 2014	$ 342,352