Regulatory Matters (Details 2) (USD $)	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Regulatory Assets and Liability [Line Items]
Net Over Recovery of Two and One Years Prior Gas Cost Recovery Expense		$ 5,900,000
Gas Cost Recovery Cos of Gas Gold Two and One Years Prior		1,000,000,000
Net Over Recovery of One Year Prior and Current Year Gas Cost Recovery Expense	1,000,000
Gas Cost Recovery Cost of Cost of Gas Sold One Year Prior and Current Year	$ 700,000,000