Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Net income	$ 2.1	$ 77.6	$ 62.5	$ 84.6
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 loss	0.0	0.0	0.0	(0.1)
Defined benefit plans:
Amortization of prior service benefits included in net income, net of tax of ($0.4), ($1.3), ($0.8), ($2.7)	(0.7)	(2.4)	(1.4)	(4.7)
Amortization of net actuarial loss included in net income, net of tax of $2.0, $2.2, $4.0, $4.3	3.6	3.9	7.1	7.8
Total other comprehensive income (loss)	2.9	1.5	(62.4)	3.0
Total comprehensive income	$ 5.0	$ 79.1	$ 0.1	$ 87.6