Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (5.5)	$ (13.8)	$ (32.4)	$ (22.1)
Other comprehensive income (loss), net of tax:
Foreign currency translation gain (loss)	1.5	(2.5)	3.1	(4.3)
Cash flow hedges:
Unrealized loss on cash flow hedges arising during the period, net of tax of ($2.3), ($0.4), ($3.3), ($0.4)	(7.8)	(1.5)	(10.9)	(1.5)
Reclassification adjustment for net losses included in net income, net of tax of $0.0, $0.1	0.2	0.0	0.4	0.0
Defined benefit plans:
Net benefit arising from remeasurement during the period, net of tax of $0.0, $0.0	0.1	0.0	0.1	0.0
Amortization of prior service benefits included in net income, net of tax of ($0.2), ($0.2), ($0.3), ($0.4)	(0.5)	(0.6)	(1.0)	(1.2)
Amortization of net actuarial loss included in net income, net of tax of $0.9, $1.2, $1.7, $2.4	3.0	4.1	6.0	8.2
Total other comprehensive (loss) income	(3.5)	(0.5)	(2.3)	1.2
Total comprehensive loss	$ (9.0)	$ (14.3)	$ (34.7)	$ (20.9)