EMPLOYEE BENEFIT PLANS (Tables)

12 Months Ended

Dec. 31, 2015

Compensation and Retirement Disclosure [Abstract]

Schedule of changes in benefit obligations, fair value of plan assets, and funded status of plan

The changes in the benefit obligation, the changes in fair value of plan assets, and the funded status of the Company’s Pension and Post-Retirement Medical Plans as of and for the years ended December 31, 2015 and 2014 were as follows:

	Pension Plans						Post-Retirement Medical Plan
	2015			2014			2015			2014
Change in benefit obligation:
Benefit obligation at beginning of year	$	81,098		$	53,350		$	14,740		$	8,225
Service cost	24,298			19,407			967			1,099
Interest cost	2,974			2,404			558			520
Plan amendments	—			529			1,533			3,911
Benefit payments	(2,231		)	(2,634		)	(381		)	(215		)
Actuarial loss (gain)	(6,128		)	8,042			312			1,200
Projected benefit obligation at end of year	$	100,011		$	81,098		$	17,729		$	14,740
Change in plan assets:
Fair value of plan assets at beginning of year	$	40,956		$	25,050		$	—		$	—
Actual return on plan assets	(13		)	1,822			—			—
Benefits paid	(2,231		)	(2,634		)	(381		)	(215		)
Employer contributions	18,790			16,718			381			215
Fair value of plan assets at end of year	$	57,502		$	40,956		$	—		$	—
Reconciliation of funded status:
Fair value of plan assets at end of year	$	57,502		$	40,956		$	—		$	—
Less: benefit obligations at end of year	100,011			81,098			17,729			14,740
Funded status at end of year	$	(42,509	)	$	(40,142	)	$	(17,729	)	$	(14,740	)

Schedule of expected benefit payments

Benefit payments, which reflect expected future services, that the Company expects to pay are as follows for the years ended December 31:

	Pension Benefits		Post-Retirement Medical Plan
2016	$	11,125	$	843
2017	8,271		1,141
2018	9,403		1,296
2019	10,694		1,580
2020	13,429		1,788
Years 2021-2025	88,044		8,835

Schedule of net periodic benefit cost

The components of net periodic benefit cost were as follows for the years ended December 31, 2015, 2014 and 2013:

	Pension Benefits									Post-Retirement Medical Plan
	2015			2014			2013			2015		2014			2013
Components of net period benefit cost:
Service cost	$	24,298		$	19,407		$	14,794		$	967	$	1,099		$	726
Interest cost	2,974			2,404			992			558		520			334
Expected return on plan assets	(3,422		)	(2,156		)	(550		)	—		—			—
Amortization of prior service cost	53			39			11			326		258			—
Amortization of actuarial loss (gain)	1,228			1,033			421			—		(4		)	—
Net periodic benefit cost	$	25,131		$	20,727		$	15,668		$	1,851	$	1,873		$	1,060

Schedule of pre-tax amounts recognized in other comprehensive income (loss)

The pre-tax amounts recognized in other comprehensive income (loss) for the years ended December 31, 2015, 2014 and 2013 were as follows:

	Pension Benefits									Post-Retirement Medical Plan
	2015			2014			2013			2015			2014			2013
Prior service costs (credits)	$	—		$	529		$	—		$	1,533		$	3,911		$	(860	)
Net actuarial loss (gain)	(2,220		)	8,151			8,235			312			1,201			(1,654		)
Amortization of losses and prior service cost	(1,281		)	(1,072		)	(432		)	(326		)	(255		)	—
Total changes in other comprehensive loss (income)	$	(3,501	)	$	7,608		$	7,803		$	1,519		$	4,857		$	(2,514	)

Schedule of pre-tax amounts in accumulated other comprehensive loss not yet recognized as components of net periodic costs

The pre-tax amounts in accumulated other comprehensive loss as of December 31, 2015 and 2014 that have not yet been recognized as components of net periodic costs were as follows:

	Pension Benefits						Post-Retirement Medical Plan
	2015			2014			2015			2014
Prior service (costs) credits	$	(529	)	$	(582	)	$	(3,999	)	$	(2,793	)
Net actuarial (loss) gain	(19,841		)	(23,762		)	(391		)	(78		)
Total	$	(20,370	)	$	(24,344	)	$	(4,390	)	$	(2,871	)

Schedule of pre-tax amounts in accumulated other comprehensive loss to be recognized over next fiscal year

The following pre-tax amounts included in accumulated other comprehensive loss as of December 31, 2015 are expected to be recognized as components of net period benefit cost during the year ended December 31, 2016:

	Pension Benefits			Post-Retirement Medical Plan
Amortization of prior service costs (credits)	$	(53	)	$	(436	)
Amortization of net actuarial loss (gain)	(775		)	—
Total	$	(828	)	$	(436	)

Schedule of assumptions used

The weighted average assumptions used to determine the net periodic benefit costs for the years ended December 31, 2015, 2014 and 2013 were as follows:

	Qualified Plan						Supplemental Plan						Post-Retirement Medical Plan
	2015		2014		2013		2015		2014		2013		2015		2014		2013
Discount rate:
Service Cost	4.25	%	4.55	%	3.45	%	4.30	%	4.55	%	3.45	%	4.32	%	4.55	%	3.45	%
Effective rate for interest cost	3.31	%	4.55	%	3.45	%	3.16	%	4.55	%	3.45	%	3.09	%	4.55	%	3.45	%
Effective rate for interest on service cost	3.51	%	4.55	%	3.45	%	3.37	%	4.55	%	3.45	%	4.04	%	4.55	%	3.45	%
Expected long-term rate of return on plan assets	7.00	%	6.70	%	3.50	%	—	%	—	%	—	%	—	%	—	%	—	%
Rate of compensation increase	4.81	%	4.64	%	4.00	%	5.50	%	4.64	%	4.00	%	—	%	—	%	—	%

The weighted average assumptions used to determine the benefit obligations as of December 31, 2015 and 2014 were as follows:

	Qualified Plan				Supplemental Plan				Post-Retirement Medical Plan
	2015		2014		2015		2014		2015		2014
Discount rate - Benefit obligations	4.17	%	3.70	%	4.22	%	3.70	%	3.76	%	3.70	%
Rate of compensation increase	4.81	%	4.96	%	5.50	%	4.96	%	—	%	—	%

Schedule of assumed health care cost trend rates

The assumed health care cost trend rates as of December 31, 2015 and 2014 were as follows:

	Post-Retirement Medical Plan
	2015		2014
Health care cost trend rate assumed for next year	6.1	%	6.7	%
Rate to which the cost trend rate was assumed to decline (the ultimate trend rate)	4.5	%	4.5	%
Year that the rate reached the ultimate trend rate	2038		2027

Schedule of effect of one-percentage-point change in assumed health care cost trend rates

Assumed health care costs trend rates have a significant effect on the amounts reported for retiree health care plans. A one percentage-point change in assumed health care costs trend rates would have the following effects on the medical post-retirement benefits:

	1% Increase		1% Decrease
Effect on total of service and interest cost components	$	21	$	(20	)
Effect on accumulated post-retirement benefit obligation	413		(388		)

Schedule of fair value of assets of the Company's Qualified Plan

The tables below present the fair values of the assets of the Company’s Qualified Plan as of December 31, 2015 and 2014 by level of fair value hierarchy. Assets categorized in Level 1 of the hierarchy are measured at fair value using a market approach based on published net asset values of mutual funds. As noted above, the Company’s post retirement medical plan is funded on a pay-as-you-go basis and has no assets.

	Fair Value Measurements Using Quoted Prices in Active Markets (Level 1)
	December 31,
	2015		2014
Equities:
Domestic equities	$	17,660	$	12,682
Developed international equities	8,320		5,600
Emerging market equities	4,017		2,629
Global low volatility equities	4,930		3,478
Fixed-income	22,495		16,517
Cash and cash equivalents	80		50
Total	$	57,502	$	40,956