Financial Instruments and Risk Management (Concentration of Credit Risk) (Details)	12 Months Ended
	Dec. 31, 2013
Natural Gas Distribution
Concentration Risk [Line Items]
Number of customers	422,000
Largest Oil & Gas Purchasers, One | Accounts receivable
Concentration Risk [Line Items]
Concentration of credit risk	35.00%
Largest Oil & Gas Purchasers, One | Total operating revenues
Concentration Risk [Line Items]
Concentration of credit risk	25.00%
Largest Oil & Gas Purchasers, Two | Accounts receivable
Concentration Risk [Line Items]
Concentration of credit risk	12.00%
Largest Oil & Gas Purchasers, Two | Total operating revenues
Concentration Risk [Line Items]
Concentration of credit risk	10.00%
Largest Oil & Gas Purchasers, Three | Accounts receivable
Concentration Risk [Line Items]
Concentration of credit risk	9.00%