Long Term Debt (Textuals) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Line of Credit Facility [Line Items]
Borrowed under existing credit facility	12.0
Maximum Borrowing Capacity	75.0
CEI Credit Facility [Member]
Line of Credit Facility [Line Items]
Borrowed under existing credit facility	22.0
Avaliable Borrowing Capacity	53.0
Maximum Borrowing Capacity	75.0
Minimum Leverage [Member] | September 30, 2013 And December 31, 2013 and Thereafter [Member]
Line of Credit Facility [Line Items]
Interest Coverge Ratio	2.50 to 1.0
Maximum Leverage [Member] | December 31, 2013 And Thereafter [Member]
Line of Credit Facility [Line Items]
Leverage Ratios	5.25 to 1.0
Minimum Interest Coverage [Member] | September 30, 2013 And December 31, 2013 [Member]
Line of Credit Facility [Line Items]
Interest Coverge Ratio	2.25 to 1.0
Minimum Interest Coverage [Member] | Prior To December 31, 2013 [Member]
Line of Credit Facility [Line Items]
Leverage Ratios	5.50 to 1.0
Credit Facility [Member]
Line of Credit Facility [Line Items]
Borrowed under existing credit facility	12.0
Outstanding letter of credit	57.1
Avaliable Borrowing Capacity	565.9
Maximum Borrowing Capacity	635.0
Available Additional Borrowings	377.3