Segment Information - Sales by Product (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Total sales	$ 916,034	$ 772,031
Specialty Products & Electronics
Segment Reporting Information [Line Items]
Total sales	315,067	378,269
Transit Products
Segment Reporting Information [Line Items]
Total sales	258,419	48,795
Brake Products
Segment Reporting Information [Line Items]
Total sales	180,459	158,033
Remanufacturing, Overhaul & Build
Segment Reporting Information [Line Items]
Total sales	129,058	151,906
Other
Segment Reporting Information [Line Items]
Total sales	$ 33,031	$ 35,028