Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 44.7	$ 9.7
Receivables, less allowances of $9.5 and $9.9	173.2	178.6
Inventory, materials and supplies	24.1	22.7
Prepaid expenses	20.6	15.0
Other current assets	3.9	3.9
Total current assets	266.5	229.9
Property, plant and equipment, net	1,107.7	1,085.5
Investment in CyrusOne	0.0	128.0
Goodwill	18.6	14.3
Deferred income taxes, net	62.2	64.5
Other noncurrent assets	19.0	18.8
Total assets	1,474.0	1,541.0
Current liabilities
Current portion of long-term debt	8.2	7.5
Accounts payable	120.3	105.9
Unearned revenue and customer deposits	38.2	36.3
Accrued taxes	11.8	12.9
Accrued interest	11.9	12.7
Accrued payroll and benefits	31.6	25.7
Other current liabilities	35.2	31.9
Total current liabilities	257.2	232.9
Long-term debt, less current portion	1,113.7	1,199.1
Pension and postretirement benefit obligations	194.1	197.7
Other noncurrent liabilities	36.4	33.0
Total liabilities	1,601.4	1,662.7
Shareowners' Deficit [Abstract]
Preferred stock, 2,357,299 shares authorized, 155,250 shares (3,105,000 depositary shares) of 6 3/4% Cumulative Convertible Preferred Stock issued and outstanding at March 31, 2017 and December 31, 2016; liquidation preference $1,000 per share ($50 per depositary share)	129.4	129.4
Common shares, $.01 par value; 96,000,000 shares authorized; 42,133,326 and 42,056,237 shares issued; 42,133,326 and 42,056,237 shares outstanding at March 31, 2017 and December 31, 2016	0.4	0.4
Additional paid-in capital	2,570.1	2,570.9
Accumulated deficit	(2,671.7)	(2,732.1)
Accumulated other comprehensive loss	(155.6)	(90.3)
Total shareowners' deficit	(127.4)	(121.7)
Total liabilities and shareowners' deficit	$ 1,474.0	$ 1,541.0