Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net income	$ 60.4	$ 7.0
Other comprehensive (loss) income, net of tax:
Unrealized gains on Investment in CyrusOne, net of tax of $4.4	8.3	0.0
Reclassification adjustment for gain on sale of Investment in CyrusOne included in net income, net of tax of ($41.3)	(76.4)	0.0
Foreign currency translation loss	0.0	(0.1)
Defined benefit plans:
Amortization of prior service benefits included in net income, net of tax of ($0.4), ($1.4)	(0.7)	(2.3)
Amortization of net actuarial loss included in net income, net of tax of $2.0, $2.1	3.5	3.9
Total other comprehensive (loss) income	(65.3)	1.5
Total comprehensive (loss) income	$ (4.9)	$ 8.5