PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Tables)

12 Months Ended

Dec. 31, 2015

Compensation and Retirement Disclosure [Abstract]

Schedule of components of projected benefit obligations and plan assets, and the funded status of the plans

The components of projected benefit obligations and plan assets, and the funded status of the RIGP and the Retiree Medical Plan (“the Plans”) were as follows for the periods indicated (in thousands):

	RIGP						Retiree Medical Plan
	Year Ended December 31,						Year Ended December 31,
	2015			2014			2015			2014
Change in benefit obligation:
Benefit obligation at beginning of year	$	17,988		$	17,180		$	36,117		$	35,149
Service cost	11			94			365			345
Interest cost	551			553			1,334			1,420
Plan participants’ contributions	—			—			510			456
Actuarial loss (gain)	346			770			(3,573		)	(188		)
Settlements	(469		)	—			—			—
Benefit payments	(1,022		)	(609		)	(1,023		)	(1,065		)
Benefit obligation at end of year	$	17,405		$	17,988		$	33,730		$	36,117
Change in plan assets:
Fair value of plan assets at beginning of year	$	6,743		$	6,003		$	—		$	—
Actual return on plan assets	(373		)	152			—			—
Plan participants’ contributions	—			—			510			456
Employer contributions	665			1,197			513			609
Settlements	(469		)	—			—			—
Benefit payments	(1,022		)	(609		)	(1,023		)	(1,065		)
Fair value of plan assets at end of year	$	5,544		$	6,743		$	—		$	—
Funded status at end of year	$	(11,861	)	$	(11,245	)	$	(33,730	)	$	(36,117	)

Schedule of amounts recognized in consolidated balance sheets for the Plans

Amounts recognized in our consolidated balance sheets for the Plans consist of the following at the dates indicated below (in thousands):

	RIGP						Retiree Medical Plan
	December 31,						December 31,
	2015			2014			2015			2014
Liabilities:
Accrued employee benefit liabilities - current	$	—		$	—		$	(2,948	)	$	(2,998	)
Accrued employee benefit liabilities - noncurrent	(11,861		)	(11,245		)	(30,782		)	(33,119		)
Total	$	(11,861	)	$	(11,245	)	$	(33,730	)	$	(36,117	)
AOCI:
Net actuarial loss	$	5,804		$	6,062		$	1,289		$	5,061
Total	$	5,804		$	6,062		$	1,289		$	5,061

Schedule of accumulated benefit obligation in excess of plan assets

Information regarding the accumulated benefit obligation in excess of plan assets for the RIGP is as follows at the dates indicated (in thousands):

	RIGP
	December 31,
	2015		2014
Projected benefit obligation	$	17,405	$	17,988
Accumulated benefit obligation (1)	13,357		13,602
Fair value of plan assets	5,544		6,743

____________________________

(1) The accumulated benefit obligation does not include an assumption for future compensation increases.

Schedule of weighted average assumptions used in determining net periodic benefit cost for the Plans

The weighted average assumptions used in determining net periodic benefit cost for the Plans were as follows for the periods indicated:

	RIGP						Retiree Medical Plan
	Year Ended December 31,						Year Ended December 31,
	2015		2014		2013		2015		2014		2013
Discount rate	3.3	%	3.5	%	2.7	%	3.9	%	4.4	%	3.6	%
Expected return on plan assets	5.8	%	5.8	%	5.8	%	N/A		N/A		N/A
Rate of compensation increase	3.0	%	3.0	%	3.0	%	3.0	%	3.0	%	3.0	%

Schedule of assumptions used in determining benefit obligations for the Plans

The assumptions used in determining benefit obligations for the Plans were as follows at the dates indicated:

	RIGP				Retiree Medical Plan
	December 31,				December 31,
	2015		2014		2015		2014
Discount rate	3.5	%	3.3	%	4.1	%	3.9	%
Rate of compensation increase	3.0	%	3.0	%	3.0	%	3.0	%

Schedule of effect of 1% movement in assumed health care cost trend rates

Based on a hypothetical 1% movement in the assumed health care cost trend rates, the change in costs would have had the following effects on the December 31, 2015 results (in thousands):

	1% Increase		1% (Decrease)
Effect on total service cost and interest cost components	$	56	$	(50	)
Effect on postretirement benefit obligation	778		(700		)

Schedule of components of net periodic benefit cost and other changes recognized in OCI

The components of the net periodic benefit cost and other changes recognized in OCI for the Plans were as follows for the periods indicated (in thousands):

	RIGP									Retiree Medical Plan
	Year Ended December 31,									Year Ended December 31,
	2015			2014			2013			2015			2014			2013
Components of net periodic benefit cost:
Service cost	$	11		$	94		$	217		$	365		$	345		$	431
Interest cost	551			553			538			1,334			1,420			1,409
Expected return on plan assets	(334		)	(333		)	(393		)	—			—			—
Amortization of prior service credit	—			—			—			—			—			(1,624		)
Actuarial loss due to settlements	469			—			773			—			—			—
Amortization of unrecognized loss	842			667			1,232			199			31			1,193
Net periodic benefit cost	$	1,539		$	981		$	2,367		$	1,898		$	1,796		$	1,409
Other changes in plan assets and benefit obligations recognized in OCI:
Net actuarial loss (gain)	$	1,053		$	951		$	(3,298	)	$	(3,573	)	$	(188	)	(7,756		)
Amortization of unrecognized loss	(842		)	(667		)	(1,232		)	(199		)	(31		)	(1,193		)
Actuarial loss due to settlements	(469		)	—			(773		)	—			—			—
Amortization of prior service credit	—			—			—			—			—			1,624
Total recognized in OCI	$	(258	)	$	284		$	(5,303	)	$	(3,772	)	$	(219	)	$	(7,325	)
Total recognized in net period benefit cost and OCI	$	1,281		$	1,265		$	(2,936	)	$	(1,874	)	$	1,577		$	(5,916	)

Schedule of amounts included in OCI that will be recognized in consolidated statement of operations

We expect that the following amounts, currently included in OCI, for the Plans will be recognized in our consolidated statement of operations during the year ending December 31, 2016 (in thousands):

	RIGP		Retiree Medical Plan
Amortization of unrecognized loss	$	923	$	—

Schedule of expected employer contributions to benefit plans

We estimate the following benefit payments, which reflect expected future service, as appropriate, will be paid for the Plans in the years indicated below as such (in thousands):

	RIGP		Retiree Medical Plan
2016	$	1,827	$	3,009
2017	2,147		2,946
2018	1,825		2,912
2019	1,871		2,893
2020	1,681		2,801
Thereafter	5,922		11,500

Summary of investments in the RIGP

A summary of investments in the RIGP are as follows at the dates indicated (in thousands):

	December 31, 2015				December 31, 2014
	Level 1		Level 3		Level 1		Level 3
Mutual fund - fixed-income securities	$	2,759	$	—	$	3,107	$	—
Mutual fund - money market	465		—		660		—
Coal lease	—		2,320		—		2,976
Fair value of plan assets	$	3,224	$	2,320	$	3,767	$	2,976

Summary of the activity in Level 3 pension assets

The following table summarizes the activity in our Level 3 pension assets for the periods indicated (in thousands):

	Year Ended December 31,
	2015			2014
Beginning balance, January 1	$	2,976		$	3,303
Lease payments received	393			307
Unrealized loss	(656		)	(327		)
Transfers out of Level 3	(393		)	(307		)
Ending balance, December 31	$	2,320		$	2,976