Acquisitions - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	Oct. 30, 2015	Oct. 08, 2015	Jun. 17, 2015	Feb. 04, 2015
Business Acquisition [Line Items]
Goodwill	$ 867,623,000	$ 858,532,000
Escrow deposits	212,772,000	$ 202,942,000
Acquired indefinite-lived intangible assets	60,000,000
Trade Names
Business Acquisition [Line Items]
Acquired indefinite-lived intangible assets	5,600,000
Customer Relationships
Business Acquisition [Line Items]
Acquired indefinite-lived intangible assets	$ 52,600,000
Average useful life, years	20 years
Noncompete Agreements
Business Acquisition [Line Items]
Acquired indefinite-lived intangible assets	$ 300,000
Average useful life, years	5 years
Customer Backlog
Business Acquisition [Line Items]
Acquired indefinite-lived intangible assets	$ 1,500,000
Acquisitions other than Faiveley
Business Acquisition [Line Items]
Escrow deposits	$ 35,400,000
RMS
Business Acquisition [Line Items]
Purchase price, net of cash acquired			$ 18,710,000
Goodwill			8,847,000
Goodwill tax deduction			$ 0
Track IQ
Business Acquisition [Line Items]
Purchase price, net of cash acquired				$ 9,312,000
Goodwill				6,649,000
Goodwill tax deduction				$ 6,600,000
RCL
Business Acquisition [Line Items]
Purchase price, net of cash acquired						$ 78,011,000
Goodwill						14,787,000
Goodwill tax deduction						$ 14,800,000
MTC
Business Acquisition [Line Items]
Purchase price, net of cash acquired					$ 23,360,000
Goodwill					12,141,000
Goodwill tax deduction					$ 0