Long Term Debt (Details Textuals) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
Pre May Amendment [Member]
Line of Credit Facility [Line Items]
Leverage Ratios	5.0 to 1.0
Post May Amendment [Member]
Line of Credit Facility [Line Items]
Leverage Ratios	5.5 to 1.0
During Acquisition [Member]
Line of Credit Facility [Line Items]
Leverage Ratios	5.5 to 1.0
Line Of Credit Amendment Date 1 [Member]
Line of Credit Facility [Line Items]
Line of credit facility, amended date	January 2012
Line Of Credit Amendment Date 2 [Member]
Line of Credit Facility [Line Items]
Line of credit facility, amended date	May 2012
Line Of Credit Amendment Date 3 [Member]
Line of Credit Facility [Line Items]
Line of credit facility, amended date	August 2012
Allowance For Construction Cost	20.0
Percentage Of Amount of Material Projects	15.00%
Preamendment Credit Facility [Member]
Line of Credit Facility [Line Items]
Preamendment borrowing capacity	485.0
Postamendment Credit Facility [Member]
Line of Credit Facility [Line Items]
Postamendment borrowing capacity	635.0
2016 Letter of Credit [Member]
Line of Credit Facility [Line Items]
Borrowed under existing credit facility	5.5
Outstanding letter of credit	61.6
Avaliable Borrowing Capacity	567.9