(LOSS) EARNINGS PER COMMON SHARE - Computation of Basic and Diluted Net (Loss) Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	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
Numerator:
Net (loss) income attributable to Stericycle, Inc.	$ (318.4)	$ 23.5	$ 27.7	$ 22.5	$ 89.2	$ 39.0	$ (144.0)	$ 58.2	$ (244.7)	$ 42.4	$ 206.3
Mandatory convertible preferred stock dividend		(8.4)	(8.3)	(8.8)	(8.8)	(8.9)	(9.2)	(9.4)	(25.5)	(36.3)	(39.4)
Gain on repurchase of preferred stock									16.9	17.3	11.3
Net (loss) income attributable to Stericycle, Inc. common shareholders	$ (318.4)	$ 17.5	$ 26.6	$ 21.0	$ 83.3	$ 35.5	$ (148.8)	$ 53.4	$ (253.3)	$ 23.4	$ 178.2
Denominator:
Denominator for basic (loss) earnings per share-weighted average shares (in shares)									87.1	85.3	84.9
Effect of dilutive securities:
Stock-based compensation awards (2)										0.3	0.7
Denominator for diluted (loss) earnings per share - adjusted weighted average shares and after assumed exercises (in shares)									87.1	85.6	85.6
(Loss) earnings per share – Basic (in dollars per share)	$ (3.51)	$ 0.20	$ 0.31	$ 0.25	$ 0.98	$ 0.42	$ (1.74)	$ 0.63	$ (2.91)	$ 0.27	$ 2.10
(Loss) earnings per share – Diluted (in dollars per share)	$ (3.51)	$ 0.20	$ 0.31	$ 0.25	$ 0.97	$ 0.41	$ (1.74)	$ 0.62	$ (2.91)	$ 0.27	$ 2.08