Discontinued Operations - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2018	Dec. 31, 2017
Net loss attributable to noncontrolling interest	$ 0.5	$ 0.5	$ 0.4
Additional paid in capital		2,297.3			$ 1,565.4
Other accrued expenses		19.2			15.0
LifeWorks [Member]
Additional paid in capital				$ 95.7
Other accrued expenses		$ 0.2			$ 0.3