Income Taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Deferred tax assets:
Net operating loss carryforwards	$ 452,300,000	$ 410,800,000
Pension and postretirement benefits	81,900,000	144,600,000
Equity method investment in CyrusOne	41,500,000	0
Other	63,200,000	69,900,000
Total deferred tax assets	638,900,000	625,300,000
Valuation allowance	(68,300,000)	(56,800,000)
Total deferred tax assets, net of valuation allowance	570,600,000	568,500,000
Deferred tax liabilities:
Property, plant and equipment	171,800,000	125,100,000
Federal deferred liability on state deferred tax assets	3,500,000	7,200,000
Other	300,000	1,600,000
Total deferred tax liabilities	175,600,000	133,900,000
Net deferred tax assets	395,000,000	434,600,000
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Federal tax operating loss carryforwards	1,100,000,000
Federal tax operating loss carryforwards, deferred tax asset value	388,400,000
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	16,500,000
State tax credits	11,100,000
Deferred Tax Assets, Operating Loss Carryforwards, Foreign, State and Local Tax	63,900,000
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. federal statutory rate	35.00%	35.00%	35.00%
State and local income taxes, net of federal income tax	1.50%	3.90%	2.90%
Change in valuation allowance, net of federal income tax	(15.80%)	(2.30%)	(4.40%)
State net operating loss adjustments	2.70%	3.70%	2.70%
Nondeductible interest expense	(11.40%)	18.10%	15.00%
Unrecognized tax benefit changes	(2.10%)	2.20%	2.80%
Nondeductible compensation	(2.50%)	2.70%	2.10%
Foreign	(0.70%)	3.50%	0.10%
Other differences, net	(2.30%)	2.00%	1.10%
Effective tax rate	4.40%	68.80%	57.30%
Current:
Federal	0	1,800,000	0
State and local	0	1,600,000	400,000
Total current	0	3,400,000	400,000
Investment tax credits	(200,000)	(300,000)	(300,000)
Deferred:
Federal	(13,000,000)	21,800,000	24,300,000
State and local	(3,700,000)	2,000,000	3,400,000
Foreign	300,000	(500,000)	100,000
Total deferred	(16,400,000)	23,300,000	27,800,000
Valuation allowance	14,100,000	(1,700,000)	(2,900,000)
Total	(2,500,000)	24,700,000	25,000,000
Income Tax Provision (Benefit) Charged to Continuing Operations, Accumulated Other Comprehensive Income (Loss) or Additional Paid-In Capital [Abstract]
Income tax expense (benefit)	(2,500,000)	24,700,000	25,000,000
Accumulated other comprehensive income (loss)	42,100,000	(400,000)	(26,500,000)
Excess tax benefits on stock option exercises	(500,000)	(2,400,000)	0
Income Tax Uncertainties [Abstract]
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	23,500,000	22,300,000
Balance, beginning of year	22,800,000	21,800,000	20,500,000
Change in tax positions for the current year	1,300,000	1,400,000	1,300,000
Change in tax positions for prior years	0	(400,000)	0
Balance, end of year	$ 24,100,000	$ 22,800,000	$ 21,800,000
Maximum [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2023
Minimum [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2021