Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2018

Compensation And Retirement Disclosure [Abstract]

Changes in Accumulated Benefit Obligation and Fair Value of Qualified Trust Assets (Pension Plan only) and Statement of Funded (Unfunded) Status for Pension Plan and PRB Plan

The following table provides a reconciliation of changes in the accumulated benefit obligations and fair value of qualified trust assets (Pension Plan only) and a statement of funded (unfunded) status for the Pension Plan and the PRB Plan as of and for the periods stated.

	Pension Plan						PRB Plan
	2018			2017			2018			2017
Change in benefit obligation
Benefit obligation, beginning of year	$	3,273		$	3,398		$	457		$	540
Service cost		—			—			3			22
Interest cost		94			121			5			21
Actuarial (gain) loss		(694	)		323			(36	)		(120	)
Benefit payments		(1,295	)		(581	)		(6	)		(6	)
Curtailment/termination (gain)		—			—			(352	)		—
Settlement loss		221			12			—			—
Benefit obligation, end of year		1,599			3,273			71			457
Change in plan assets
Fair value of plan assets, beginning of year		2,465			2,690			—			—
Actual (loss) return on plan assets		(54	)		356			—			—
Employer contributions		—			—			6			6
Benefits payments		(1,295	)		(581	)		(6	)		(6	)
Fair value of plan assets, end of year		1,116			2,465			—			—
(Unfunded) funded status, end of year	$	(483	)	$	(808	)	$	(71	)	$	(457	)

Amounts Recognized in Accumulated Other Comprehensive Loss (Income)

	Pension Plan				PRB Plan
	Year Ended December 31,				Year Ended December 31,
	2018		2017		2018			2017
Amounts recognized in accumulated other comprehensive loss (income)
Net loss (gain)	$	447	$	1,187	$	(354	)	$	(344	)
Prior service cost		—		—		—			—
Net obligation at transition		—		—		—			—
Amount recognized	$	447	$	1,187	$	(354	)	$	(344	)

Components of Net Periodic Benefit Cost (Gain)

Components of net periodic benefit cost (gain)
Service cost	$	—		$	—		$	3		$	22
Interest cost		94			121			5			21
Expected return on plan assets		(153	)		(167	)		—			—
Amortization of prior service cost		—			—			—			—
Amortization of net obligation at transition		—			—			(26	)		(11	)
Curtailment/termination gain		—			—			(352	)		—
Recognized net loss due to settlement		422			195			—			—
Recognized net actuarial loss		51			81			—			—
Net periodic benefit cost (gain)		414			230			(370	)		32

Other Changes in Plan Assets and Benefit Obligations Recognized in Accumulated Other Comprehensive (Income) Loss

Other changes in plan assets and benefit obligations recognized in accumulated other comprehensive (income) loss
Net gain		(739	)		(130	)		(10	)		(109	)
Amortization of prior service cost		—			—			—			—
Amortization of net obligation at transition		—			—			—			—
Total recognized in other comprehensive loss (income)		(739	)		(130	)		(10	)		(109	)
Total recognized in net periodic benefit cost and other comprehensive loss (income)	$	(325	)	$	100		$	(380	)	$	(77	)

Schedule of Actuarial Assumptions

The following table provides the actuarial assumptions used to derive the information reported in the consolidated financial statements as of and for the years ended December 31, 2018 and 2017.

	Pension Plan						PRB Plan
	As of and for the year ended December 31,						As of and for the year ended December 31,
	2018			2017			2018			2017
Discount rate used for net periodic pension cost		3.50	%		4.00	%		4.25	%		4.00	%
Discount rate used for disclosure		4.25	%		3.50	%		4.25	%		3.50	%
Expected return on plan assets		7.25	%		7.25	%	N/A			N/A
Rate of compensation increase	N/A			N/A			N/A			N/A
Rate of compensation increase for net periodic    pension cost	N/A			N/A			N/A			N/A
Expected future interest crediting rate		3.00	%		3.00	%	N/A			N/A

Estimated Future Benefit Payments for Pension Plan and PRB Plan

The following table provides estimated future benefit payments (cash) for the Pension Plan and PRB Plan for the periods presented.

	Pension Plan		PRB Plan
2019	$	298	$	7
2020		139		7
2021		103		7
2022		107		7
2023		365		6
2024 - 2028		854		27