Pension Plans and Other Postretirement Benefits (Details-6) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Expected Cash Flows
Expected employer contributions for next fiscal year	$ 0
Cash contributions to pension and other postretirement plans	34,765,000	28,857,000	23,670,000
Components of Net Periodic Benefit Cost
Transition obligation straight-line amortization period	20 years
How 1% increase or decrease in health care cost trends could impact postretirement benefits [Abstract]
1% increase	1,104,000
1% decrease	(879,000)
Deferred Pension and OPRB Costs
Deferred pension and ORPB costs, recovered in rates	1,200,000	1,200,000
Pension Benefits [Member]
Expected Cash Flows
Employer contributions	30,878,000	20,815,000
Benefit Payments
Defined benefit plan expected future benefit payments, 2014	11,474,000
Defined benefit plan expected future benefit payments, 2015	12,223,000
Defined benefit plan expected future benefit payments, 2016	12,844,000
Defined benefit plan expected future benefit payments, 2017	13,633,000
Defined benefit plan expected future benefit payments, 2018	14,755,000
Defined benefit plan expected future benefit payments, 2019-2023	87,676,000
Components of Net Periodic Benefit Cost
Service cost	7,705,000	7,139,000	6,013,000
Interest cost	12,656,000	12,704,000	12,281,000
Expected return on assets	(19,027,000)	(15,182,000)	(14,034,000)
Special termination benefits	0	0	13,000
Amortization of:
Transition obligation	0	0	0
Prior service cost	314,000	430,000	433,000
Actuarial loss	8,014,000	8,288,000	3,771,000
Net periodic benefit cost	9,662,000	13,379,000	8,477,000
Weighted-average assumptions used to determine net periodic cost:
Discount rate	4.09%	4.50%	5.36%
Long-term rate of return	8.10%	8.10%	8.25%
Rate of compensation increase	4.60%	4.59%	4.59%
Postretirement Benefits [Member]
Expected Cash Flows
Employer contributions	2,811,000	8,059,000
Benefit Payments
Defined benefit plan expected future benefit payments, 2014	2,733,000
Defined benefit plan expected future benefit payments, 2015	2,837,000
Defined benefit plan expected future benefit payments, 2016	3,062,000
Defined benefit plan expected future benefit payments, 2017	3,474,000
Defined benefit plan expected future benefit payments, 2018	3,909,000
Defined benefit plan expected future benefit payments, 2019-2023	25,244,000
Components of Net Periodic Benefit Cost
Service cost	2,380,000	2,528,000	1,920,000
Interest cost	3,871,000	4,431,000	3,980,000
Expected return on assets	(2,176,000)	(1,741,000)	(1,584,000)
Special termination benefits	0	0	0
Amortization of:
Transition obligation	3,000	425,000	427,000
Prior service cost	110,000	110,000	110,000
Actuarial loss	1,236,000	2,346,000	566,000
Net periodic benefit cost	5,424,000	8,099,000	5,419,000
Weighted-average assumptions used to determine net periodic cost:
Discount rate	4.14%	4.55%	5.42%
Long-term rate of return	6.79%	7.26%	7.39%
Gross Postretirement Benefits [Member]
Benefit Payments
Defined benefit plan expected future benefit payments, 2014	2,924,000
Defined benefit plan expected future benefit payments, 2015	3,056,000
Defined benefit plan expected future benefit payments, 2016	3,308,000
Defined benefit plan expected future benefit payments, 2017	3,740,000
Defined benefit plan expected future benefit payments, 2018	4,198,000
Defined benefit plan expected future benefit payments, 2019-2023	27,110,000
Expected Medicare Part D Subsidy [Member]
Benefit Payments
Defined benefit plan expected future benefit payments, 2014	(191,000)
Defined benefit plan expected future benefit payments, 2015	(219,000)
Defined benefit plan expected future benefit payments, 2016	(246,000)
Defined benefit plan expected future benefit payments, 2017	(266,000)
Defined benefit plan expected future benefit payments, 2018	(289,000)
Defined benefit plan expected future benefit payments, 2019-2023	$ (1,866,000)