Condensed Consolidated Statements of Comprehensive Income (Loss) - 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)		$ 4.4	$ (20.6)	$ (63.7)	$ (54.6)
Items of other comprehensive income (loss) before income taxes:
Change in foreign currency translation adjustment		9.8	23.1	(16.2)	43.9
Change in unrealized loss from invested customer trust funds		(6.0)	(7.8)	(24.5)	(10.0)
Change in pension liability adjustment	[1]	2.9	2.5	8.7	7.6
Other comprehensive income (loss) before income taxes		6.7	17.8	(32.0)	41.5
Income tax benefit, net		(0.9)	(1.8)	(2.3)	(3.0)
Other comprehensive income (loss) after income taxes		7.6	19.6	(29.7)	44.5
Comprehensive income (loss)		12.0	(1.0)	(93.4)	(10.1)
Comprehensive (loss) income attributable to noncontrolling interest			(0.2)	(0.5)	0.2
Comprehensive income (loss) attributable to Ceridian		$ 12.0	$ (0.8)	$ (92.9)	$ (10.3)

[1] The amount of the pension liability adjustment recognized in the condensed consolidated statements of operations within selling, general, and administrative expense was $3.0 and $2.6 during the three months ended September 30, 2018, and 2017, respectively, and $9.0 and $7.8 during the nine months ended September 30, 2018, and 2017, respectively.