Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net (loss) income	$ (69.8)	$ 40.0	$ 103.0
Other comprehensive income (loss), net of tax:
Unrealized gains on Investment in CyrusOne, net of tax of $4.4, $36.9	0.0	8.3	68.1
Reclassification adjustment for gain on sale of Investment in CyrusOne included in net income, net of tax of ($41.3)	0.0	(76.4)	0.0
Foreign currency translation (loss) gain	(6.5)	0.2	(0.1)
Cash flow hedge:
Unrealized loss on cash flow hedge arising during the period, net of tax of ($1.4)	(4.8)	0.0	0.0
Reclassification adjustment for net losses included in net income, net of tax of $0.3	0.9	0.0	0.0
Defined benefit plans:
Net (loss) gain arising from remeasurement during the period, net of tax of ($1.6), $0.8, $3.6	(5.5)	2.8	6.6
Amortization of prior service benefits included in net income, net of tax of ($0.7), ($1.6), ($5.2)	(2.4)	(2.9)	(9.4)
Amortization of net actuarial loss included in net income, net of tax of $4.7, $7.9, $8.5	16.4	14.3	15.5
Reclassification adjustment for pension settlement charges included in net income, net of tax of $0.0, $1.5	0.1	2.5	0.0
Total other comprehensive (loss) income, net of tax	(1.8)	(51.2)	80.7
Total comprehensive (loss) income	$ (71.6)	$ (11.2)	$ 183.7