QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 799.9	$ 833.1	$ 845.8	$ 830.1	$ 852.7	$ 854.9	$ 883.3	$ 895.0	$ 3,308.9	$ 3,485.9	$ 3,580.7
Gross profit	279.5	295.3	302.6	297.1	328.7	335.5	353.3	358.5	1,174.5	1,376.0	1,462.5
Goodwill impairment	207.4			20.9	358.7				228.3	358.7	65.0
Divestiture losses, net of gains	24.9	83.2	0.3	(5.4)	(0.2)	1.6	7.3	4.1	103.0	12.8	9.5
Loss on early extinguishment of debt			23.1						23.1
Net (loss) income attributable to Stericycle, Inc.					(318.4)	23.5	27.7	22.5	(346.8)	(244.7)	42.4
Preferred stock dividend						(8.4)	(8.3)	(8.8)		(25.5)	(36.3)
Net (loss) income attributable to Stericycle, Inc. common shareholders	$ (219.3)	$ (59.2)	$ (30.5)	$ (37.8)	$ (318.4)	$ 17.5	$ 26.6	$ 21.0	$ (346.8)	$ (253.3)	$ 23.4
(Loss) earnings per share - Basic (in dollars per share)	$ (2.41)	$ (0.65)	$ (0.33)	$ (0.42)	$ (3.51)	$ 0.20	$ 0.31	$ 0.25	$ (3.81)	$ (2.91)	$ 0.27
(Loss) earnings per share - Diluted (in dollars per share)	$ (2.41)	$ (0.65)	$ (0.33)	$ (0.42)	$ (3.51)	$ 0.20	$ 0.31	$ 0.25	$ (3.81)	$ (2.91)	$ 0.27