CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 23.5	$ 39.0	$ 73.6	$ (46.6)
Other comprehensive income (loss):
Foreign currency translation adjustments	3.0	30.2	(56.9)	80.8
Amortization of cash flow hedge into income, net of tax expense ($0.1 and $0.2, and $0.3 and $0.5) for the three and nine months ended September 30, 2018 and 2017, respectively)	0.3	0.3	0.8	0.8
Change in fair value of cash flow hedge, net of tax expense ($0.0 and $0.0, and $0.0 and $0.1 for the three and nine months ended September 30, 2018 and 2017, respectively)				0.2
Total other comprehensive income (loss)	3.3	30.5	(56.1)	81.8
Comprehensive Income	26.8	69.5	17.5	35.2
Less: comprehensive income (loss) attributable to noncontrolling interests		0.4	(0.7)	1.1
Comprehensive income attributable to Stericycle, Inc. common shareholders	$ 26.8	$ 69.1	$ 18.2	$ 34.1