CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net (loss) income	$ (59.0)	$ 23.5	$ (126.8)	$ 73.6
Other comprehensive (loss) income:
Foreign currency translation adjustments	(28.9)	3.0	(22.8)	(56.9)
Amortization of cash flow hedge into income, net of tax expense ($0.0 and $0.1 and $0.2 and $0.3) for the three and nine months ended September 30, 2019 and 2018, respectively		0.3	0.4	0.8
Change in fair value of cash flow hedge, net of tax expense ($0.0 and $0.0 and $0.1 and $0.0) for the three and nine months ended September 30, 2019 and 2018, respectively			0.2
Reclassification of cash flow hedge, net of tax expense ($1.1) for the nine months ended September 30, 2019 to Net (loss)			2.3
Total other comprehensive (loss) income	(28.9)	3.3	(19.9)	(56.1)
Comprehensive (loss) income	(87.9)	26.8	(146.7)	17.5
Less: comprehensive income (loss) attributable to noncontrolling interests	0.1		0.9	(0.7)
Comprehensive (loss) income attributable to Stericycle, Inc. common shareholders	$ (88.0)	$ 26.8	$ (147.6)	$ 18.2