Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2015

Compensation and Retirement Disclosure [Abstract]

Schedule of amounts recognized in balance sheet

Changes in benefit obligation and plan assets for the years ended December 31, 2015 and 2014, and amounts recognized in the Consolidated Balance Sheets at December 31, 2015 and 2014, were as follows:

	Pension Benefits						Other Postretirement Benefits
	2015			2014			2015			2014
	(In thousands)
Change in benefit obligation:
Benefit obligation at beginning of year	$	475,337		$	402,772		$	99,012		$	81,726
Service cost	86			129			1,816			1,518
Interest cost	17,141			17,682			3,607			3,521
Plan participants' contributions	—			—			1,408			1,399
Actuarial (gain) loss	(24,875		)	80,520			(5,873		)	18,024
Benefits paid	(24,729		)	(25,766		)	(7,236		)	(7,176		)
Benefit obligation at end of year	442,960			475,337			92,734			99,012
Change in net plan assets:
Fair value of plan assets at beginning of year	354,363			334,844			87,586			84,543
Actual gain (loss) on plan assets	(10,879		)	24,500			258			7,527
Employer contribution	13,912			20,785			577			1,293
Plan participants' contributions	—			—			1,408			1,399
Benefits paid	(24,729		)	(25,766		)	(7,236		)	(7,176		)
Fair value of net plan assets at end of year	332,667			354,363			82,593			87,586
Funded status - under	$	(110,293	)	$	(120,974	)	$	(10,141	)	$	(11,426	)
Amounts recognized in the Consolidated Balance Sheets at December 31:
Other assets (noncurrent)	$	—		$	—		$	5,095		$	4,345
Other accrued liabilities (current)	—			—			(421		)	(322		)
Other liabilities (noncurrent)	(110,293		)	(120,974		)	(14,815		)	(15,449		)
Net amount recognized	$	(110,293	)	$	(120,974	)	$	(10,141	)	$	(11,426	)
Amounts recognized in accumulated other comprehensive (income) loss consist of:
Actuarial loss	$	208,671		$	207,430		$	22,484		$	25,779
Prior service cost (credit)	—			294			(14,374		)	(15,744		)
Total	$	208,671		$	207,724		$	8,110		$	10,035

The projected benefit obligation, accumulated benefit obligation and fair value of plan assets for the pension plans with accumulated benefit obligations in excess of plan assets

The pension plans all have accumulated benefit obligations in excess of plan assets. The projected benefit obligation, accumulated benefit obligation and fair value of plan assets for these plans at December 31 were as follows:

	2015		2014
	(In thousands)
Projected benefit obligation	$	442,960	$	475,337
Accumulated benefit obligation	$	442,960	$	475,337
Fair value of plan assets	$	332,667	$	354,363

Components of net periodic benefit cost

Components of net periodic benefit cost (credit) for the Company's pension and other postretirement benefit plans for the years ended December 31 were as follows:

	Pension Benefits									Other Postretirement Benefits
	2015			2014			2013			2015			2014			2013
	(In thousands)
Components of net periodic benefit cost (credit):
Service cost	$	86		$	129		$	155		$	1,816		$	1,518		$	1,675
Interest cost	17,141			17,682			16,249			3,607			3,521			3,215
Expected return on assets	(22,254		)	(21,218		)	(19,917		)	(4,795		)	(4,617		)	(4,343		)
Amortization of prior service cost (credit)	36			71			71			(1,371		)	(1,393		)	(1,457		)
Recognized net actuarial loss	7,016			4,869			7,173			1,960			649			1,814
Curtailment loss	258			—			—			—			—			—
Net periodic benefit cost (credit), including amount capitalized	2,283			1,533			3,731			1,217			(322		)	904
Less amount capitalized	316			388			727			120			(21		)	164
Net periodic benefit cost (credit)	1,967			1,145			3,004			1,097			(301		)	740
Other changes in plan assets and benefit obligations recognized in accumulated other comprehensive (income) loss:
Net (gain) loss	8,257			77,238			(60,173		)	(1,336		)	15,114			(30,461		)
Amortization of actuarial loss	(7,016		)	(4,869		)	(7,173		)	(1,960		)	(649		)	(1,814		)
Amortization of prior service (cost) credit	(294		)	(71		)	(71		)	1,371			1,393			1,457
Total recognized in accumulated other comprehensive (income) loss	947			72,298			(67,417		)	(1,925		)	15,858			(30,818		)
Total recognized in net periodic benefit cost (credit) and accumulated other comprehensive (income) loss	$	2,914		$	73,443		$	(64,413	)	$	(828	)	$	15,557		$	(30,078	)

Weighted average assumptions used to determine benefit obligations and net periodic benefit costs

Weighted average assumptions used to determine benefit obligations at December 31 were as follows:

	Pension Benefits				Other Postretirement Benefits
	2015		2014		2015		2014
Discount rate	4.00	%	3.70	%	4.06	%	3.74	%
Expected return on plan assets	6.75	%	7.00	%	5.75	%	6.00	%
Rate of compensation increase	N/A		N/A		3.00	%	3.00	%

Weighted average assumptions used to determine net periodic benefit cost for the years ended December 31 were as follows:

	Pension Benefits				Other Postretirement Benefits
	2015		2014		2015		2014
Discount rate	3.70	%	4.53	%	3.74	%	4.48	%
Expected return on plan assets	7.00	%	7.00	%	6.00	%	6.00	%
Rate of compensation increase	N/A		N/A		3.00	%	3.00	%

Health care rate assumptions for the Company's other postretirement benefit plans

Health care rate assumptions for the Company's other postretirement benefit plans as of December 31 were as follows:

				2015					2014
Health care trend rate assumed for next year	4.0	%	–	8.0	%	4.0	%	–	7.0	%
Health care cost trend rate - ultimate	5.0	%	–	6.0	%	5.0	%	–	6.0	%
Year in which ultimate trend rate achieved				2021					2017

Assumed health care cost trend rates

Assumed health care cost trend rates may have a significant effect on the amounts reported for the health care plans. A one percentage point change in the assumed health care cost trend rates would have had the following effects at December 31, 2015:

	1 Percentage  Point Increase		1 Percentage Point Decrease
	(In thousands)
Effect on total of service and interest cost components	$	203	$	(169	)
Effect on postretirement benefit obligation	$	4,006	$	(3,407	)

The fair value of the pension and postretirement net plan assets by class

The fair value of the Company's pension plans' assets (excluding cash) by class were as follows:

	Fair Value Measurements  at December 31, 2015, Using
	Quoted Prices in Active Markets for Identical Assets  (Level 1)		Significant Other Observable Inputs  (Level 2)		Significant Unobservable  Inputs  (Level 3)		Balance at December 31, 2015
	(In thousands)
Assets:
Cash equivalents	$	—	$	8,379	$	—	$	8,379
Equity securities:
U.S. companies	15,135		—		—		15,135
International companies	2,332		—		—		2,332
Collective and mutual funds*	154,400		63,568		—		217,968
Corporate bonds	—		62,145		—		62,145
Municipal bonds	—		11,680		—		11,680
U.S. Government securities	5,288		6,823		—		12,111
Total assets measured at fair value	$	177,155	$	152,595	$	—	$	329,750

* Collective and mutual funds invest approximately 19 percent in common stock of large-cap U.S. companies, 6 percent in common stock of mid-cap U.S. companies, 16 percent in corporate bonds, 29 percent in common stock of international companies, 16 percent in cash equivalents and 14 percent in other investments.

	Fair Value Measurements  at December 31, 2014, Using
	Quoted Prices in Active Markets for Identical Assets  (Level 1)		Significant Other Observable Inputs  (Level 2)		Significant Unobservable  Inputs  (Level 3)		Balance at December 31, 2014
	(In thousands)
Assets:
Cash equivalents	$	—	$	5,631	$	—	$	5,631
Equity securities:
U.S. companies	39,077		—		—		39,077
International companies	5,189		—		—		5,189
Collective and mutual funds*	132,403		77,449		—		209,852
Corporate bonds	—		59,471		—		59,471
Municipal bonds	—		10,462		—		10,462
U.S. Government securities	15,001		6,849		—		21,850
Total assets measured at fair value	$	191,670	$	159,862	$	—	$	351,532

* Collective and mutual funds invest approximately 13 percent in common stock of large-cap U.S. companies, 13 percent in U.S. Government securities, 23 percent in corporate bonds, 33 percent in common stock of international companies and 18 percent in other investments.

The estimated fair values of the Company's other postretirement benefit plans' assets are determined using the market approach.

The estimated fair value of the other postretirement benefit plans' Level 2 cash equivalents is valued at the net asset value of shares held at year end, based on published market quotations on active markets, or using other known sources including pricing from outside sources. Units of this fund can be redeemed on a daily basis at their net asset value and have no redemption restrictions. The assets are invested in high-quality, short-term money market instruments that consist of municipal obligations. There are no unfunded commitments related to this fund.

The estimated fair value of the other postretirement benefit plans' Level 1 equity securities is based on the closing price reported on the active market on which the individual securities are traded.

The estimated fair value of the other postretirement benefit plans' Level 2 insurance contract is based on contractual cash surrender values that are determined primarily by investments in managed separate accounts of the insurer. These amounts approximate fair value. The managed separate accounts are valued based on other observable inputs or corroborated market data.

Though the Company believes the methods used to estimate fair value are consistent with those used by other market participants, the use of other methods or assumptions could result in a different estimate of fair value. For the years ended December 31, 2015 and 2014, there were no transfers between Levels 1 and 2.

The fair value of the Company's other postretirement benefit plans' assets (excluding cash) by asset class were as follows:

	Fair Value Measurements  at December 31, 2015, Using
	Quoted Prices in Active Markets for Identical Assets  (Level 1)		Significant Other Observable Inputs  (Level 2)		Significant Unobservable Inputs  (Level 3)		Balance at December 31, 2015
	(In thousands)
Assets:
Cash equivalents	$	—	$	3,261	$	—	$	3,261
Equity securities:
U.S. companies	2,274		—		—		2,274
International companies	9		—		—		9
Insurance contract*	—		77,044		—		77,044
Total assets measured at fair value	$	2,283	$	80,305	$	—	$	82,588

* The insurance contract invests approximately 19 percent in common stock of large-cap U.S. companies, 22 percent in U.S. Government securities, 10 percent in mortgage-backed securities, 36 percent in corporate bonds and 13 percent in other investments.

	Fair Value Measurements  at December 31, 2014, Using
	Quoted Prices in Active Markets for Identical Assets  (Level 1)		Significant Other Observable Inputs  (Level 2)		Significant Unobservable Inputs  (Level 3)		Balance at December 31, 2014
	(In thousands)
Assets:
Cash equivalents	$	—	$	2,097	$	—	$	2,097
Equity securities:
U.S. companies	2,614		—		—		2,614
International companies	25		—		—		25
Insurance contract*	—		82,846		—		82,846
Total assets measured at fair value	$	2,639	$	84,943	$	—	$	87,582

* The insurance contract invests approximately 54 percent in common stock of large-cap U.S. companies, 11 percent in U.S. Government securities, 10 percent in mortgage-backed securities, 10 percent in corporate bonds and 15 percent in other investments.

Benefit payments expected to be paid

The following benefit payments, which reflect future service, as appropriate, and expected Medicare Part D subsidies are as follows:

Years	Pension Benefits		Other Postretirement Benefits		Expected Medicare Part D Subsidy
			(In thousands)
2016	$	24,223	$	5,234	$	197
2017	24,680		5,351		191
2018	24,980		5,420		183
2019	25,323		5,441		175
2020	25,700		5,331		168
2021 - 2025	133,029		27,261		688

Multiemployer plans

	EIN/Pension Plan Number	Pension Protection Act Zone Status		FIP/RP Status Pending/Implemented	Contributions						Surcharge Imposed	Expiration Date of Collective Bargaining Agreement
Pension Fund		2015	2014		2015		2014		2013
					(In thousands)
Edison Pension Plan	93-6061681-001	Green as of 12/31/2015	Green as of 12/31/2014	No	$	5,517	$	9,061	$	6,358	No	12/31/2017
IBEW Local No. 82 Pension Plan	31-6127268-001	Red as of 6/30/2015	Red as of 6/30/2014	Implemented	2,252		1,392		1,284		No	11/29/2015*
IBEW Local No. 246 Pension Plan	34-6582842-001	Yellow as of 5/31/2015	Yellow as of 5/31/2014	Implemented	433		694		1,848		No	10/31/2017
IBEW Local No. 357 Pension Plan A	88-6023284-001	Green	Green	No	1,896		3,575		2,348		No	5/31/2018
IBEW Local 648 Pension Plan	31-6134845-001	Red as of 2/28/2015	Red as of 2/28/2014	Implemented	745		1,110		1,489		No	9/2/2018
Idaho Plumbers and Pipefitters Pension Plan	82-6010346-001	Green as of 5/31/2015	Green as of 5/31/2014	No	1,169		1,125		1,121		No	9/30/2016
Local Union 212 IBEW Pension Trust Fund	31-6127280-001	Yellow as of 4/30/2015	Yellow as of 4/30/2014	Implemented	937		568		531		No	6/5/2016
National Automatic Sprinkler Industry Pension Fund	52-6054620-001	Red as of 12/31/2015	Red as of 12/31/2014	Implemented	677		608		583		No	3/31/2016- 7/31/2018
National Electrical Benefit Fund	53-0181657-001	Green	Green	No	5,271		6,476		5,883		No	6/30/2015*- 11/30/2019
Pension Trust Fund for Operating Engineers	94-6090764-001	Red as of 12/31/2015	Red as of 12/31/2014	Implemented	1,997		1,445		1,510		No	6/15/2015*– 6/30/2016
Operating Engineers Local 800 & WY Contractors Association, Inc. Pension Plan for Wyoming**	83-6011320-001	Red as of 12/31/2015	Red as of 12/31/2014	Implemented	—		68		76		No	10/31/2005*
Sheet Metal Workers' Pension Plan of Southern CA, AZ and NV	95-6052257-001	Red as of 12/31/2015	Red as of 12/31/2014	Implemented	714		676		512		No	6/30/2016
Southwest Marine Pension Trust	95-6123404-001	Red	Red	Implemented	26		31		42		No	1/31/2014*– 1/31/2019
Other funds					17,478		15,988		15,675
Total contributions					$	39,112	$	42,817	$	39,260

* Plan includes collective bargaining agreements which have expired. The agreements contain provisions that automatically renew the existing contracts in lieu of a new negotiated collective bargaining agreement.

** The Company withdrew from the plan as of October 26, 2014, as discussed below.

The Company was listed in the plans' Forms 5500 as providing more than 5 percent of the total contributions for the following plans and plan years:

Pension Fund	Year Contributions to Plan Exceeded More Than 5 Percent of Total Contributions (as of December 31 of the Plan's Year-End)
Edison Pension Plan	2014 and 2013
IBEW Local No. 82 Pension Plan	2014 and 2013
Local Union No. 124 IBEW Pension Trust Fund	2014 and 2013
Local Union 212 IBEW Pension Trust Fund	2014 and 2013
IBEW Local Union No. 357 Pension Plan A	2014 and 2013
IBEW Local 573 Pension Plan	2014
IBEW Local 648 Pension Plan	2014 and 2013
Idaho Plumbers and Pipefitters Pension Plan	2014
Minnesota Teamsters Construction Division Pension Fund	2014 and 2013
Operating Engineers Local 800 & WY Contractors Association, Inc. Pension Plan for Wyoming*	2014 and 2013
Pension and Retirement Plan of Plumbers and Pipefitters Union Local No. 525	2014 and 2013

* The Company withdrew from the plan as of October 26, 2014, as discussed below.