Fair Value Measurements (Details Textual) (USD $) In Millions, except Per Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2011	Dec. 31, 2010
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Idled Assets, Net	$ 5.4	$ 5.5
Fair Value Measurements (Textuals) [Abstract]
Call option fair value assumptions expected dividend rate	$ 0.24
Specified Year Constant Maturity Treasury Rate One	5 years
Specified Year Constant Maturity Treasury Rate Two	3 years
Amortized costs of available for sale of assets	5.0	4.6
Fair value of the Notes	226.7	214.7
Estimated fair value of CARO liabilities	3.9	3.8
Weighted average credit-adjusted risk free rate	9.10%
Idled Assets Subsequently Placed Into Service	0.1
Assets Acquired But Not Yet Placed Into Service [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Idled Assets, Net		4.4
Tulsa Oklahoma Facility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Idled Assets, Net		$ 1.1