Selected Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended															12 Months Ended
	Jun. 30, 2018	Mar. 31, 2018		Dec. 31, 2017		Sep. 30, 2017		Jun. 30, 2017		Mar. 31, 2017		Dec. 31, 2016		Sep. 30, 2016		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016
Quarterly Financial Data [Abstract]
Sales	$ 646,119	$ 607,936		$ 571,345		$ 542,454		$ 565,025		$ 528,630		$ 487,573		$ 477,140		$ 2,367,853	$ 2,058,368	$ 2,098,436
Gross profit	235,294	219,461		192,545		184,993		180,289		186,265		147,623		143,530		832,292	657,707	616,067
Net income (loss) attributable to Kennametal	$ 68,528	$ 50,866		$ 41,601		$ 39,183		$ 24,643		$ 38,890		$ 7,262		$ (21,656)		$ 200,180	$ 49,138	$ (225,968)
Basic earnings (loss) per share attributable to Kennametal	$ 0.84	$ 0.62	[1]	$ 0.51	[1]	$ 0.48	[1]	$ 0.31	[1]	$ 0.48	[1]	$ 0.09	[1]	$ (0.27)	[1]	$ 2.45	$ 0.61	$ (2.83)
Diluted earnings (loss) per share attributable to Kennametal	$ 0.83	$ 0.61	[1]	$ 0.50	[1]	$ 0.48	[1]	$ 0.30	[1]	$ 0.48	[1]	$ 0.09	[1]	$ (0.27)	[1]	$ 2.42	$ 0.61	$ (2.83)

[1] Earnings per share amounts attributable to Kennametal for each quarter are computed using the weighted average number of shares outstanding during the quarter. Earnings per share amounts attributable to Kennametal for the full year are computed using the weighted average number of shares outstanding during the year. Thus, the sum of the four quarters’ earnings per share attributable to Kennametal does not always equal the full-year earnings per share attributable to Kennametal.