Income Taxes (Tables)

12 Months Ended

Dec. 31, 2014

Income Tax Provision (Benefit) Charged to Continuing Operations, Accumulated Other Comprehensive Income (Loss) or Additional Paid-In Capital [Abstract]

Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]

Income tax expense consisted of the following:

	Year Ended December 31,
(dollars in millions)	2014			2013			2012
Current:
Federal	$	8.0		$	—		$	1.8
State and local	1.6			—			1.6
Total current	9.6			—			3.4
Investment tax credits	(0.2		)	(0.2		)	(0.3		)
Deferred:
Federal	48.4			(13.0		)	21.8
State and local	0.7			(3.7		)	2.0
Foreign	—			0.3			(0.5		)
Total deferred	49.1			(16.4		)	23.3
Valuation allowance	(1.1		)	14.1			(1.7		)
Total	$	57.4		$	(2.5	)	$	24.7

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

The following is a reconciliation of the statutory federal income tax rate with the effective tax rate for each year:

	Year Ended December 31,
	2014		2013		2012
U.S. federal statutory rate	35.0	%	35.0	%	35.0	%
State and local income taxes, net of federal income tax	0.4		1.5		3.9
Change in valuation allowance, net of federal income tax	(3.0	)	(15.8	)	(2.3	)
State net operating loss adjustments	2.9		2.7		3.7
Nondeductible interest expense	4.0		(11.4	)	18.1
Unrecognized tax benefit changes	2.1		(2.1	)	2.2
Nondeductible compensation	1.0		(2.5	)	2.7
Foreign	—		(0.7	)	3.5
Other differences, net	0.8		(2.3	)	2.0
Effective tax rate	43.2	%	4.4	%	68.8	%

Schedule of income tax provision charged to continuing operations, accumulated other comprehensive income (loss) or additional paid-in capital [Table Text Block]

The income tax (benefit) provision was charged to continuing operations, accumulated other comprehensive income or additional paid-in capital as follows:

	Year Ended December 31,
(dollars in millions)	2014			2013			2012
Income tax (benefit) provision related to:
Continuing operations	$	57.4		$	(2.5	)	$	24.7
Accumulated other comprehensive (loss) income	(22.4		)	42.1			(0.4		)
Excess tax benefits on stock option exercises	(0.1		)	(0.5		)	(2.4		)

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

The components of our deferred tax assets and liabilities were as follows:

	December 31,
(dollars in millions)	2014			2013
Deferred tax assets:
Net operating loss carryforwards	$	286.5		$	452.3
Pension and postretirement benefits	95.5			81.9
Equity method investment in CyrusOne	64.5			41.5
Deferred gain on sale of wireless spectrum licenses	42.2			—
AMT Credit Carryforward	24.7			16.5
Other	47.4			46.7
Total deferred tax assets	560.8			638.9
Valuation allowance	(64.4		)	(68.3		)
Total deferred tax assets, net of valuation allowance	$	496.4		$	570.6
Deferred tax liabilities:
Property, plant and equipment	$	121.9		$	171.8
Other	4.9			3.8
Total deferred tax liabilities	126.8			175.6
Net deferred tax assets	$	369.6		$	395.0

Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]

A reconciliation of the unrecognized tax benefits is as follows:

	Year Ended December 31,
(dollars in millions)	2014		2013		2012
Balance, beginning of year	$	24.1	$	22.8	$	21.8
Change in tax positions for the current year	3.0		1.3		1.4
Change in tax positions for prior years	—		—		(0.4		)
Balance, end of year	$	27.1	$	24.1	$	22.8