Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (23.7)	$ (14.7)	$ (36.1)	$ (37.5)
Other comprehensive income (loss)
Translation adjustments	2.1	2.1	(13.2)	1.8
Interest rate swap adjustments	0.0	(6.9)	(11.1)	(10.6)
Other comprehensive income (loss), before tax	2.1	(4.8)	(24.3)	(8.8)
Income tax impact related to items of other comprehensive income (loss)	0.0	1.8	2.8	2.7
Other comprehensive income (loss), net of tax	2.1	(3.0)	(21.5)	(6.1)
Total comprehensive loss	(21.6)	(17.7)	(57.6)	(43.6)
Less: comprehensive income (loss) attributable to noncontrolling interests	(0.2)	0.1	(0.2)	(0.2)
Comprehensive loss attributable to Quad common shareholders	$ (21.4)	$ (17.8)	$ (57.4)	$ (43.4)