Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						4 Months Ended		12 Months Ended
	Sep. 07, 2019	Jun. 15, 2019	Mar. 23, 2019	Sep. 08, 2018	Jun. 16, 2018	Mar. 24, 2018	Dec. 28, 2019	Dec. 29, 2018	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Earnings Per Share [Abstract]
Net income	$ 6,056	$ 7,164	$ (2,429)	$ 6,419	$ 6,120	$ (102)	$ (2,042)	$ 2,601	$ 8,749	$ 15,038	$ 28,410
Less: income attributable to noncontrolling interest	87	108	83	74	121	18	108	97	386	310	287
Income attributable to Heritage-Crystal Clean, Inc. common stockholders	$ 5,969	$ 7,056	$ (2,512)	$ 6,345	$ 5,999	$ (120)	$ (2,150)	$ 2,504	$ 8,363	$ 14,728	$ 28,123
Weighted average basic shares outstanding (in shares)	23,185	23,137	23,117	23,048	23,029	22,962	23,190	23,056	23,160	23,026	22,662
Dilutive shares for share–based compensation plans (in shares)									238	308	260
Weighted average diluted shares outstanding (in shares)	23,421	23,368	23,117	23,404	23,361	22,962	23,190	23,411	23,398	23,334	22,922
Net income per share: basic (in dollars per share)	$ 0.26	$ 0.30	$ (0.11)	$ 0.28	$ 0.26	$ (0.01)	$ (0.09)	$ 0.11	$ 0.36	$ 0.64	$ 1.24
Net income per share: diluted (in dollars per share)	$ 0.25	$ 0.30	$ (0.11)	$ 0.27	$ 0.26	$ (0.01)	$ (0.09)	$ 0.11	$ 0.36	$ 0.63	$ 1.23