Income Taxes - Income Tax Reconciliation (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Computed federal income tax expense	$ 8.3	$ 0	$ 0.4
State income taxes	1.0	(0.3)	(0.6)
Non-deductible transaction costs	1.6	1.7	0.8
Charitable contribution	(0.2)	(3.5)	0
Solar tax credits	0	(2.9)	0
Other—net	(2.2)	(2.6)	0.4
Total continuing operations tax expense (benefit)	$ 8.5	$ (7.6)	$ 1.0