Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net (loss) income	$ (13.8)	$ 2.3	$ (22.1)	$ 62.9
Other comprehensive income (loss), net of tax:
Unrealized gains on Investment in CyrusOne, net of tax of $4.4	0.0	0.0	0.0	8.3
Reclassification adjustment for gain on sale of Investment in CyrusOne included in net income, net of tax of ($41.3)	0.0	0.0	0.0	(76.4)
Foreign currency translation loss	(2.5)	0.0	(4.3)	0.0
Unrealized loss on cash flow hedge arising during the period, net of tax of ($0.4), ($0.4)	(1.5)	0.0	(1.5)	0.0
Defined benefit plans:
Amortization of prior service benefits included in net income, net of tax of ($0.2), ($0.4), ($0.4), ($0.8)	(0.6)	(0.7)	(1.2)	(1.4)
Amortization of net actuarial loss included in net income, net of tax of $1.2, $2.0, $2.4, $4.0	4.1	3.6	8.2	7.1
Total other comprehensive income (loss)	(0.5)	2.9	1.2	(62.4)
Total comprehensive loss	$ (14.3)	$ 5.2	$ (20.9)	$ 0.5