Reconciliation of Basic and Diluted Shares (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share [Abstract]
Income (loss) from continuing operations, net of tax	$ 13,669	$ (32,612)	$ 41,571	$ (71,156)
Weighted-average shares outstanding - basic (in shares)	80,637	80,379	80,519	80,318
Dilutive effect of stock-based compensation (in shares)	2,499	0	2,234	0
Weighted-average shares outstanding - diluted (in shares)	83,136	80,379	82,753	80,318
Earnings (loss) from continuing operations per common share, attributable to Harsco Corporation common stockholders:
Basic (in dollars per share)	$ 0.17	$ (0.41)	$ 0.52	$ (0.89)
Diluted (in dollars per share)	$ 0.16	$ (0.41)	$ 0.50	$ (0.89)