Pension and Other Postretirement Benefits (details) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
General Discussion of Pension and Other Postretirement Benefits [Abstract]
Defined Benefit Plan Pension Plans With Accumulated Benefit Obligations In Excess Of Plan Assets Aggregate Projected Benefit Obligation Qualified Plans	$ 362,400,000		$ 404,000,000
Defined Benefit Plan, Fair Value of Plan Assets	267,062,000		249,603,000
Defined Benefit Plan Amounts That Will Be Amortized From Accumulated Other Comprehensive Income Loss In Next Fiscal Year Regulatory	9,800,000
Defined Benefit Plan Amortization Of Net Gains Losses Regulatory	9,400,000
Defined Benefit Plan Amortization Of Net Prior Service Cost Credit Regulatory	400,000
Multiemployer Plan, Period Contributions	500,000		400,000		400,000
Multiemployer Plan, Percentage of Contributions	4% to 5%
Multiemployer Plans, Withdrawal Obligation	8,300,000
Multiemployer Plans, Withdrawal Payment Per Year For Next 20 Years	600,000
Defined Contribution Plan, Cost Recognized	2,200,000		2,200,000		2,400,000
Defined Benefit Obligations Non Qualified Supplemental	28,700,000		31,900,000
Qualified Defined Benefit Plans Benefit Obligation Underfunded	95,300,000
Defined Benefit Plan Amounts Recognized In Regulatory Amortization And Other Comprehensive Income Net Prior Service Cost Credit Before Tax [Abstract]
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Recognized in Net Periodic Benefit Cost, before Tax	(7,000)		(35,000)
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, beore Tax	1,550,000		1,134,000
Accumulated other comprehensive loss	(6,358,000)		(9,291,000)		(7,800,000)
Total Amounts Reclassified Into Accumulated Other Comprehensive Income	3,302,000		(3,495,000)
Other Comprehensive Income (Loss), Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service (Cost) Credit, Tax	(1,912,000)		905,000
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	2,933,000		(1,491,000)
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Defined Benefit Plan, Amortization of Net Gains (Losses)	1,000,000
Pension and Other Postretirement Benefit Contributions [Abstract]
Payroll Overhead Charge to Construction Work Orders	30% to 40%
Defined Benefit Plan, Health Care Cost Trend Rate For Pre-65 Population Assumed for Next Fiscal Year	9.00%
Defined Benefit Plan, Health Care Cost Trend Rate For Post-65 Population Assumed for Next Fiscal Year	7.90%
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	5.00%
Defined Benefit Plan, Year that Rate Reaches Ultimate Trend Rate	2021
Other Comprehensive Income Total Reclassifications Before Tax	4,845,000		(2,396,000)
Qualified Contributions Expected During Next Fiscal Year	$15 million
Defined Benefit Plan, Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates [Abstract]
Defined Benefit Plan, Effect of One Percentage Point Increase on Service and Interest Cost Components	73,000
Defined Benefit Plan, Effect of One Percentage Point Decrease on Service and Interest Cost Components	(64,000)
Defined Benefit Plan, Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation	739,000
Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation	(660,000)
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Asset Receivable Or Payable Accrued Interest And Dividend Income	468,000		388,000
Plan Asset Receivable Or Payable Due From Broker Securities Sold	1,154,000		4,459,000
Total Pension Plan Asset Receivables	1,622,000		4,847,000
Plan Asset Receivable Or Payable Due From Broker Securities Purchased	1,178,000		935,000
Defined Benefit Plan, Fair Value of Plan Assets	267,062,000		249,603,000
Plan Asset Target Allocation [Abstract]
US Large Cap Equity Pension Plan Asset Target Allocation	13.00%
US Small Mid Cap Equity Pension Plan Asset Target Allocation	8.50%
Non US Equity Pension Plan Asset Target Allocation	13.00%
Emerging Markets Equity Pension Plan Asset Target Allocation	3.50%
Long Government Credit Pension Plan Asset Target Allocation	30.00%
High Yield Pension Plan Asset Target Allocation	5.00%
Emerging Market Debt Pension Plan Asset Target Allocation	5.00%
Real Estate Funds Pension Plan Asset Target Allocation	6.00%
Absolute Return Strategy Pension Plan Asset Target Allocation	11.00%
Real Return Strategy Pension Plan Asset Target Allocation	5.00%
Defined Benefit Plan Fair Value Of Plan Assets By Measurement Table [Abstract]
US Large Cap Equity Pension Assets	39,203,000		30,938,000
US Small Mid Cap Equity Pension Assets	30,520,000		22,936,000
Non US Equity Pension Assets	33,984,000		29,743,000
Emerging Markets Equity Pension Assets	7,405,000		8,004,000
Fixed Income Pension Assets	367,000		8,824,000
Long Government Credit Pension Assets	65,915,000		59,347,000
High Yield Bonds Pension Assets	12,890,000		12,017,000
Emerging Market Debt Pension Assets	9,987,000		11,421,000
Real Estate Funds Pension Assets	16,559,000		15,992,000
Absolute Return Strategy Pension Assets	35,339,000		32,078,000
Real Return Strategy Pension Assets	13,031,000		12,932,000
Cash And Cash Equivalents Pension Assets	1,418,000		1,459,000
Total Pension Asset Investments Net Of Receivables And Payables	266,618,000		245,691,000
Pension Plans, Defined Benefit [Member]
General Discussion of Pension and Other Postretirement Benefits [Abstract]
Defined Benefit Plan, Fair Value of Plan Assets	267,062,000		249,603,000		215,970,000
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Benefit Obligation	391,089,000		435,889,000		391,127,000
Defined Benefit Plan, Service Cost	8,698,000		8,047,000		7,122,000
Defined Benefit Plan, Interest Cost	16,400,000		17,295,000		18,134,000
Defined Benefit Plan, Actuarial Gain (Loss)	(51,043,000)		37,615,000
Defined Benefit Plan, Benefits Paid	18,855,000		18,195,000		18,269,000
Defined Benefit Plan, Actual Return on Plan Assets	22,872,000		26,683,000
Defined Benefit Plan, Contributions by Employer	13,442,000		25,145,000
Defined Benefit Plan, Funded Status of Plan	(124,027,000)		(186,286,000)
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Defined Benefit Plan, Service Cost	8,698,000		8,047,000		7,122,000
Defined Benefit Plan, Interest Cost	16,400,000		17,295,000		18,134,000
Defined Benefit Plan, Expected Return on Plan Assets	(18,721,000)		(19,082,000)		(17,867,000)
Defined Benefit Plan Amortization Of Transition Obligations	0		0		0
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	223,000		195,000		352,000
Defined Benefit Plan, Amortization of Net Gains (Losses)	18,294,000		15,631,000		11,584,000
Defined Benefit Plan Net Periodic Benefit Cost	24,894,000		22,086,000		19,325,000
Defined Benefit Plan Amount Allocated To Construction	(6,712,000)		(5,820,000)		(4,905,000)
Defined Benefit Plan Net Amount Deferred To Regulatory Balancing Account	(9,115,000)	[1]	(7,876,000)	[1]	(6,008,000)	[1]
Defined Benefit Plan Net Amount Charged To Expense	9,067,000		8,390,000		8,412,000
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	3.84%		4.51%		5.49%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	7.50%		8.00%		8.25%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	4.73%		3.85%		4.51%
Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Rate Of Compensation Low Range	3.25%		3.25%		3.25%
Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Rate Of Compensation High Range	5.00%		5.00%		5.00%
Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Rate Of Compensation Low Range	3.25%		3.25%		3.25%
Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Rate Of Compensation High Range	5.00%		5.00%		5.00%
Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Expected Long Term Return On Assets	7.50%		7.50%		8.00%
Pension and Other Postretirement Benefit Contributions [Abstract]
Qualified Defined Benefit Pension Plan Contributions	13,907,000		25,559,000
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	15,607,000
Defined Benefit Plan, Benefits Paid	18,855,000		18,195,000		18,269,000
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months	19,450,000
Defined Benefit Plan, Expected Future Benefit Payments, Year Two	20,033,000
Defined Benefit Plan, Expected Future Benefit Payments, Year Three	20,671,000
Defined Benefit Plan, Expected Future Benefit Payments, Year Four	21,424,000
Defined Benefit Plan, Expected Future Benefit Payments, Year Five	22,337,000
Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter	129,177,000
Defined Benefit Plan, Information about Plan Assets [Abstract]
Defined Benefit Plan, Fair Value of Plan Assets	267,062,000		249,603,000		215,970,000
Other Postretirement Benefit Plans, Defined Benefit [Member]
General Discussion of Pension and Other Postretirement Benefits [Abstract]
Defined Benefit Plan, Fair Value of Plan Assets	0		0		0
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Benefit Obligation	28,754,000		33,119,000		30,049,000
Defined Benefit Plan, Service Cost	656,000		592,000		614,000
Defined Benefit Plan, Interest Cost	1,157,000		1,267,000		1,404,000
Defined Benefit Plan, Actuarial Gain (Loss)	(4,283,000)		3,182,000
Defined Benefit Plan, Benefits Paid	1,895,000		1,971,000		1,870,000
Defined Benefit Plan, Actual Return on Plan Assets	0		0
Defined Benefit Plan, Contributions by Employer	1,895,000		1,971,000
Defined Benefit Plan, Funded Status of Plan	(28,754,000)		(33,119,000)
Defined Benefit Plan Amounts Recognized In Regulatory Amortization And Other Comprehensive Income Net Prior Service Cost Credit Before Tax [Abstract]
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax	(4,283,000)		3,182,000		2,225,000
Regulatory Amortization Of Defined Benefit Plan Net Transition Asset Obligation Recognized In Net Periodic Benefit Cost Before Tax	0		(411,000)		(411,000)
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Recognized in Net Periodic Benefit Cost, before Tax	(197,000)		(197,000)		(197,000)
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, beore Tax	(733,000)		(435,000)		(289,000)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, before Tax	(5,213,000)		2,139,000		1,328,000
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Defined Benefit Plan, Service Cost	656,000		592,000		614,000
Defined Benefit Plan, Interest Cost	1,157,000		1,267,000		1,404,000
Defined Benefit Plan, Expected Return on Plan Assets	0		0		0
Defined Benefit Plan Amortization Of Transition Obligations	0		411,000		411,000
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	197,000		197,000		197,000
Defined Benefit Plan, Amortization of Net Gains (Losses)	734,000		435,000		289,000
Defined Benefit Plan Net Periodic Benefit Cost	2,744,000		2,902,000		2,915,000
Defined Benefit Plan Amount Allocated To Construction	(856,000)		(882,000)		(878,000)
Defined Benefit Plan Net Amount Deferred To Regulatory Balancing Account	0	[1]	0	[1]	0	[1]
Defined Benefit Plan Net Amount Charged To Expense	1,888,000		2,020,000		2,037,000
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax	685,000		882,000
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax	4,665,000		9,681,000
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax	5,350,000		10,563,000
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	3.56%		4.33%		5.16%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	4.45%		3.56%		4.33%
Pension and Other Postretirement Benefit Contributions [Abstract]
Qualified Defined Benefit Pension Plan Contributions	1,895,000		1,971,000
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	1,892,000
Defined Benefit Plan, Benefits Paid	1,895,000		1,971,000		1,870,000
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months	1,892,000
Defined Benefit Plan, Expected Future Benefit Payments, Year Two	1,927,000
Defined Benefit Plan, Expected Future Benefit Payments, Year Three	2,001,000
Defined Benefit Plan, Expected Future Benefit Payments, Year Four	2,053,000
Defined Benefit Plan, Expected Future Benefit Payments, Year Five	2,112,000
Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter	10,823,000
Defined Benefit Plan, Information about Plan Assets [Abstract]
Defined Benefit Plan, Fair Value of Plan Assets	0		0		0
Qualified Pension Plans, Defined Benefit [Member]
General Discussion of Pension and Other Postretirement Benefits [Abstract]
Defined Benefit Plan, Fair Value of Plan Assets	267,100,000		249,600,000
Defined Benefit Plan Amounts Recognized In Regulatory Amortization And Other Comprehensive Income Net Prior Service Cost Credit Before Tax [Abstract]
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax	(51,892,000)		26,504,000		66,404,000
Regulatory Amortization Of Defined Benefit Plan Net Transition Asset Obligation Recognized In Net Periodic Benefit Cost Before Tax	0		0		0
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Recognized in Net Periodic Benefit Cost, before Tax	(230,000)		(230,000)		(230,000)
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, beore Tax	(16,744,000)		(14,482,000)		(10,731,000)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, before Tax	(68,866,000)		11,792,000		55,443,000
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax	867,000		1,097,000
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax	119,638,000		188,278,000
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax	120,505,000		189,375,000
Defined Benefit Plan, Information about Plan Assets [Abstract]
Defined Benefit Plan, Fair Value of Plan Assets	267,100,000		249,600,000
Non-Qualified Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Amounts Recognized In Regulatory Amortization And Other Comprehensive Income Net Prior Service Cost Credit Before Tax [Abstract]
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax	(3,302,000)		3,511,000		2,948,000
Regulatory Amortization Of Defined Benefit Plan Net Transition Asset Obligation Recognized In Net Periodic Benefit Cost Before Tax	0		0		0
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Recognized in Net Periodic Benefit Cost, before Tax	7,000		35,000		(122,000)
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, beore Tax	(1,550,000)		(1,150,000)		(854,000)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, before Tax	(4,845,000)		2,396,000		1,972,000
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax	(5,000)		(12,000)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax	10,475,000		15,327,000
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax	10,470,000		15,315,000
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Fair Value Of Plan Assets By Measurement Table [Abstract]
US Large Cap Equity Pension Assets	39,124,000		29,047,000
US Small Mid Cap Equity Pension Assets	30,465,000		21,624,000
Non US Equity Pension Assets	16,782,000		13,931,000
Emerging Markets Equity Pension Assets	7,405,000		8,004,000
Fixed Income Pension Assets	0		0
Long Government Credit Pension Assets	33,152,000		30,098,000
High Yield Bonds Pension Assets	0		0
Emerging Market Debt Pension Assets	9,987,000		11,421,000
Real Estate Funds Pension Assets	16,559,000		15,992,000
Absolute Return Strategy Pension Assets	0		0
Real Return Strategy Pension Assets	13,031,000		12,932,000
Cash And Cash Equivalents Pension Assets	0		0
Total Pension Asset Investments Net Of Receivables And Payables	166,505,000		143,049,000
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Fair Value Of Plan Assets By Measurement Table [Abstract]
US Large Cap Equity Pension Assets	79,000		1,891,000
US Small Mid Cap Equity Pension Assets	55,000		1,312,000
Non US Equity Pension Assets	17,202,000		15,812,000
Emerging Markets Equity Pension Assets	0		0
Fixed Income Pension Assets	367,000		8,824,000
Long Government Credit Pension Assets	32,763,000		29,249,000
High Yield Bonds Pension Assets	12,890,000		12,017,000
Emerging Market Debt Pension Assets	0		0
Real Estate Funds Pension Assets	0		0
Absolute Return Strategy Pension Assets	35,339,000		32,078,000
Real Return Strategy Pension Assets	0		0
Cash And Cash Equivalents Pension Assets	1,418,000		1,459,000
Total Pension Asset Investments Net Of Receivables And Payables	100,113,000		102,642,000
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Fair Value Of Plan Assets By Measurement Table [Abstract]
US Large Cap Equity Pension Assets	0		0
US Small Mid Cap Equity Pension Assets	0		0
Non US Equity Pension Assets	0		0
Emerging Markets Equity Pension Assets	0		0
Fixed Income Pension Assets	0		0
Long Government Credit Pension Assets	0		0
High Yield Bonds Pension Assets	0		0
Emerging Market Debt Pension Assets	0		0
Real Estate Funds Pension Assets	0		0
Absolute Return Strategy Pension Assets	0		0
Real Return Strategy Pension Assets	0		0
Cash And Cash Equivalents Pension Assets	0		0
Total Pension Asset Investments Net Of Receivables And Payables	$ 0		$ 0

[1] Effective January 1, 2011, the OPUC approved the deferral of certain pension expenses above or below the amount set in rates, with recovery of these deferred amounts through the implementation of a balancing account, which includes the expectation of lower net periodic benefit costs in future years. Deferred pension expense balances include accrued interest at the utility’s authorized rate of return. See Note 2.