Employee Benefit Plans and Insurance (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 4.6	$ 2.6	$ 0.9
Self Insurance Program, Major Medical and Hospitialization, Liability per Employee or Dependent per Year, Maximum	150,000
Employee-related Liabilities, Health Insurance, Self-insurance Program, Current	2.5	1.9
Self Insurance Program, Workers' Compensation Coverage per Incident, Maximum	500,000
Self Insurance Program, General Liability Insurance, Deductible per Occurrence	250,000
Accrued Insurance Premiums and Deductibles, Self Insurance Program, Workers' Compensation, General and Auto Liability Insurance	$ 6.1	$ 6.5