Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (13.6)	$ (17.7)	$ (46.0)	$ (39.8)
Other comprehensive income (loss), net of tax:
Foreign currency translation (loss) gain	(1.0)	1.7	2.1	(2.6)
Cash flow hedges:
Unrealized (loss) gain on cash flow hedges arising during the period, net of tax of ($0.9), $0.3, ($4.2), ($0.1)	(3.0)	1.1	(13.9)	(0.4)
Reclassification adjustment for net losses included in net income, net of tax of $0.2, $0.2, $0.3, $0.2	0.4	0.5	0.8	0.5
Defined benefit plans:
Net benefit arising from remeasurement during the period, net of tax of $0.0	0.0	0.0	0.1	0.0
Amortization of prior service benefits included in net income, net of tax of ($0.2), ($0.1), ($0.5), ($0.5)	(0.4)	(0.6)	(1.4)	(1.8)
Amortization of net actuarial loss included in net income, net of tax of $1.0, $1.1, $2.7, $3.5	2.9	4.1	8.9	12.3
Total other comprehensive (loss) income	(1.1)	6.8	(3.4)	8.0
Total comprehensive loss	$ (14.7)	$ (10.9)	$ (49.4)	$ (31.8)