Gas Reserves and Other Investments (details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Gas Reserves [Abstract]
Term Of Gas Reserves Contract In Years	30 years
Peak Volume Of Gas Reserves Contract	13.00%
Gas Reserves Average Volume Over First Ten Years	approximately 8 to 10 percent
Annual Gas Reserves Investment	approximately $45 million to $55 million per year for five years
Total Expected Gas Reserves Investment	$ 250,000,000
Maximum Regulatory Variance Exposure	10,000,000
Changes In Fair Value Deferred As Income Statement For Contracts Not Qualifying For Hedge Accounting And To Other Comprehensive Income For Contracts Qualifying For Hedge Accounting Percent	10.00%
Net Gas Reserves Investment	36,300,000
Deferred Taxes Related To Gas Reserves	15,600,000
Palomar [Abstract]
Equity Method Investment Ownership Percentage	50.00%
Palomar West Zone Impairment	300,000
Palomar East Zone Impairment	1,000,000
Equity Method Investment Underlying Equity In Net Assets	13,500,000
Equity Method Investment Exposure	13,200,000
Other Investments [Abstract]
Life Insurance, Corporate or Bank Owned, Amount	51,911,000	51,090,000
Equity Method Investments	14,340,000	15,742,000
Other Investments	2,012,000	2,262,000
Other investments	$ 68,263,000	$ 69,094,000