EMPLOYEE BENEFIT PLANS (Tables)

12 Months Ended

Dec. 31, 2012

EMPLOYEE BENEFIT PLANS

Summary of target asset allocation percentages for major categories of the pension plan

	Minimum Exposure			Target			Maximum Exposure
Fixed Income		35	%		40	%		45	%
Total Domestic Equity		40	%		50	%		60	%
Small Cap Stocks		10	%		15	%		20	%
Large Cap Stocks		30	%		35	%		45	%
Non-U.S. Equities		5	%		10	%		15	%

Schedule of fair value plan assets

	Pension Benefits										Other Benefits
	2012		%			2011		%			2012		%			2011		%
Fixed Income	$	79,391		39	%	$	79,859		51	%	$	22,845		61	%	$	16,006		59	%
Domestic Equity
Small Cap Stocks		33,949					27,262					—					—
Large Cap Stocks		69,406					40,689					14,563					10,972
Total Domestic Equity		103,355		51	%		67,951		44	%		14,563		39	%		10,972		41	%
Non U.S. Equities		20,201		10	%		7,939		5	%		—		0	%		—		0	%
Total Plan Assets	$	202,947		100	%	$	155,749		100	%	$	37,408		100	%	$	26,978		100	%

Schedule of reconciliation of the funded status of the plans with the accrued pension liability and the net postretirement benefit liability

	Pension Benefits						Other Benefits
	2012			2011			2012			2011
Change in projected benefit obligation:
Beginning of year	$	346,305		$	269,940		$	69,107		$	45,944
Service cost		15,450			11,713			4,399			3,199
Interest cost		15,287			14,683			3,139			2,872
Assumption change		24,269			59,028			7,673			12,600
Experience (gain) loss		4,833			(6,030	)		1,250			5,705
Benefits paid, net of retiree premiums		(4,023	)		(3,029	)		(1,147	)		(1,213	)
End of year	$	402,121		$	346,305		$	84,421		$	69,107
Change in plan assets:
Fair value of plan assets at beginning of year	$	155,749		$	139,034		$	26,978		$	21,178
Actual return on plan assets		21,979			555			2,788			64
Employer contributions		29,242			19,189			8,789			6,949
Retiree contributions and Medicare part D subsidies		—			—			1,255			1,130
Benefits paid		(4,023	)		(3,029	)		(2,402	)		(2,343	)
Fair value of plan assets at end of year	$	202,947		$	155,749		$	37,408		$	26,978
Funded status(1)	$	(199,174	)	$	(190,556	)	$	(47,013	)	$	(42,129	)
Unrecognized actuarial loss		133,579			123,177			40,449			34,515
Unrecognized prior service cost		41,972			47,976			421			537
Unrecognized transition obligation		—			—			9			285
Net amount recognized	$	(23,623	)	$	(19,403	)	$	(6,134	)	$	(6,792	)

(1)

The short-term portion of the pension benefits was $1,286 and $692 as of December 31, 2012 and 2011, respectively.

Schedule of amounts recognized in consolidated balance sheets

	Pension Benefits						Other Benefits
	2012			2011			2012			2011
Prepaid (Accrued) benefit costs	$	—		$	—		$	(6,723	)	$	(6,792	)
Accrued benefit liability		(199,174	)		(190,556	)		(47,013	)		(35,337	)
Regulatory asset		175,551			171,153			47,602			35,337
Net amount recognized	$	(23,623	)	$	(19,403	)	$	(6,134	)	$	(6,792	)

Schedule of actuarial assumptions used in determining the benefit obligation

	Pension Benefits						Other Benefits
	2012			2011			2012			2011
Weighted average assumptions as of December 31:
Discount rate		4.10	%		4.40	%		4.20	%		4.50	%
Long-term rate of return on plan assets		7.00	%		7.00	%		6.00	%		6.25	%
Rate of compensation increases		3.50	%		3.50	%		—			—
Cost of living adjustment		3.00	%		3.00	%		—			—

Schedule of sensitivity of pension amounts to changes in actuarial assumptions

	Increase/(Decrease) in Pension Actuarial Assumption			Increase/(Decrease) in 2012 Net Periodic Pension Benefit Cost			Increase/(Decrease) in Projected Pension Benefit Obligation as of December 31, 2012
Discount rate		(0.5	)%	$	4,280		$	40,189
Long-term rate of return on plan assets		(0.5	)%		826			—
Rate of compensation increases		(0.5	)%		(1,929	)		(11,227	)
Cost of living adjustment		(0.5	)%		(3,291	)		(24,427	)
Discount rate		0.5	%		(3,793	)		(35,196	)
Long-term rate of return on plan assets		0.5	%		(825	)		—
Rate of compensation increases		0.5	%		2,095			12,099

Components of net periodic benefit costs for the pension and other postretirement plans

	Pension Plan									Other Benefits
	2012			2011			2010			2012			2011			2010
Service cost	$	15,450		$	11,713		$	10,076		$	4,399		$	3,199		$	2,491
Interest cost		15,287			14,683			13,701			3,139			2,872			2,329
Expected return on plan assets		(11,558	)		(8,949	)		(8,228	)		(1,832	)		(1,372	)		(1,119	)
Net amortization and deferral		14,283			10,387			9,224			2,425			1,592			1,081
Net periodic benefit cost	$	33,462		$	27,834		$	24,773		$	8,131		$	6,291		$	4,782

Schedule of actuarial assumptions used in determining the net periodic benefit costs

	Pension Benefits						Other Benefits
	2012			2011			2012			2011
Weighted average assumptions as of December 31:
Discount rate		4.40	%		5.60	%		4.50	%		5.60	%
Long-term rate of return on plan assets		7.00	%		6.75	%		6.25	%		6.00	%
Rate of compensation increases		3.50	%		4.00	%		—			—

Schedule of the effect of a one-percentage point change in assumed health care cost trends

	1-Percentage Point Increase		1-Percentage Point Decrease
Effect on total service and interest costs	$	2,036	$	(1,506	)
Effect on accumulated postretirement benefit obligation	$	18,576	$	(14,147	)