SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Change in Accounting Estimate [Line Items]
Net sales	$ 1,117,876	$ 1,077,814	$ 1,111,680	$ 1,056,177	$ 1,075,538	$ 957,931	$ 932,253	$ 916,034	$ 4,363,547	$ 3,881,756	$ 2,931,188
Gross profit	297,025	302,012	323,967	310,881	268,440	253,203	273,963	269,707	1,233,885	1,065,313	924,239
Income from operations	93,456	125,179	123,523	131,279	91,545	101,666	113,356	114,512	473,437	421,079	456,607
Net income attributable to Wabtec shareholders	$ 34,423	$ 87,739	$ 84,416	$ 88,366	$ 48,948	$ 67,399	$ 72,025	$ 73,889	$ 294,944	$ 262,261	$ 304,887
Basic earnings from operations per common share (in dollars per share)	$ 0.36	$ 0.91	$ 0.88	$ 0.92	$ 0.51	$ 0.70	$ 0.75	$ 0.77	$ 3.06	$ 2.74	$ 3.37
Diluted earnings from operations per common share (in dollars per share)	$ 0.36	$ 0.91	$ 0.87	$ 0.92	$ 0.51	$ 0.70	$ 0.75	$ 0.77	$ 3.05	$ 2.72	$ 3.34
Restatement Adjustment
Change in Accounting Estimate [Line Items]
Income from operations					$ (14,800)