Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net (loss) income	$ (11.2)	$ 18.8	$ 51.3	$ 103.4
Other comprehensive income (loss), net of tax:
Unrealized gains on Investment in CyrusOne, net of tax of $4.4	0.0	0.0	8.3	0.0
Reclassification adjustment for gain on sale of Investment in CyrusOne included in net income, net of tax of ($41.3)	0.0	0.0	(76.4)	0.0
Foreign currency translation gain (loss)	0.1	0.0	0.1	(0.1)
Defined benefit plans:
Amortization of prior service benefits included in net income, net of tax of ($0.4), ($1.2), ($1.2), ($3.9)	(0.8)	(2.4)	(2.2)	(7.1)
Amortization of net actuarial loss included in net income, net of tax of $1.9, $2.1, $5.9, $6.4	3.6	3.8	10.7	11.6
Total other comprehensive income (loss)	2.9	1.4	(59.5)	4.4
Total comprehensive (loss) income	$ (8.3)	$ 20.2	$ (8.2)	$ 107.8