Income Taxes - Reconciliation of Effective Income Tax Rate (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax Expense
Federal income tax (expense) benefit at the statutory rate, percent	35.00%	(35.00%)	35.00%
Federal income tax (expense) benefit at the statutory rate	$ 6.3	$ (11.4)	$ 18.4
State income taxes, net of federal tax benefits, percent	(24.20%)	(14.90%)	5.80%
State income taxes, net of federal tax benefits	(4.3)	(4.8)	3.0
Non-deductible expenses and other, percent	(4.70%)	(2.70%)	(1.40%)
Non-deductible expenses and other	(0.8)	(0.8)	(0.7)
Cancellation of stock options, percent	(11.50%)	(3.70%)	0.00%
Cancellation of stock options	(2.1)	(1.2)	0
Non-deductible donation of land, percent	0.00%	(3.50%)	0.00%
Non-deductible donation of land	0	(1.2)	0
Dividend income from foreign subsidiary, percent	0.00%	0.00%	(3.50%)
Dividend income from foreign subsidiary	0	0	(1.8)
Reserves for unrecognized tax benefits, percent	(0.70%)	1.70%	4.10%
Reserves for unrecognized tax benefits	(0.1)	0.5	2.1
Credits, percent	3.30%	3.70%	13.70%
Credits	(0.5)	(1.2)	(7.2)
Change in valuation allowance/reserve of deferred tax assets, percent	(23.20%)	47.20%	(31.40%)
Change in valuation allowance/reserve of deferred tax assets	(4.2)	15.4	(16.5)
Income tax (expense) benefit from continuing operations, percent	(26.00%)	(7.20%)	22.30%
Income tax (expense) benefit from continuing operations	$ (4.7)	$ (2.3)	$ 11.7