Post-Retirement Benefits (Tables)

12 Months Ended

Dec. 31, 2017

Retiree Medical Plan

Post-Retirement Benefits

Schedule of the plan's funded status and amounts recognized in the Company's accompanying consolidated financial statements

	December 31,
(Dollars in thousands)	2017		2016		2015
Change in benefit obligation:
Benefit obligation at beginning of year	$	393	$	422	$	436
Interest cost		13		13		12
Actuarial loss		(29)		1		19
Benefits paid		(40)		(43)		(45)
Benefit obligation at end of year		337		393		422
Change in plan assets:
Fair value of plan assets at beginning of year		—		—		—
Employer contribution		40		43		45
Benefits paid		(40)		(43)		(45)
Fair value of plan assets at end of year		—		—		—
Funded status	$	(337)	$	(393)	$	(422)

Schedule of weighted average assumptions used to determine benefit obligations and net periodic benefit cost

	Year Ended December 31,
	2017		2016		2015
Weighted-average assumptions used to determine benefit obligation at December 31:
Discount rate	3.20	%	3.50	%	3.30	%
Weighted-average assumptions used to determine net periodic benefit cost for years ended December 31:
Discount rate	3.50	%	3.30	%	3.00	%
Assumed health care cost trend rates at December 31:
Health care cost trend rate assumed for next year	5.00	%	5.00	%	5.00	%

Schedule of components of net periodic benefit cost and other amounts recognized in other comprehensive income

	Year Ended December 31,
(Dollars in thousands)	2017		2016		2015
Interest cost	$	13	$	13	$	12
Recognized net actuarial loss		10		10		9
Net periodic benefit cost		23		23		21
Net loss		(29)		1		19
Amortization of loss		(10)		(10)		(9)
Total amount recognized in other comprehensive income		(39)		(9)		10
Total recognized in net periodic benefit cost and other comprehensive income	$	(16)	$	14	$	31

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

	One-Percentage Point
(Dollars in thousands)	Increase		Decrease
Effect on total of interest cost	$	1	$	(1)
Effect on postretirement benefit obligation		19		(17)

Schedule of estimated future benefit payments (including expected future service as appropriate)

(Dollars in thousands)
2018	$	38
2019		37
2020		36
2021		34
2022		33
2023-2027		131
	$	309

Retiree Welfare Plan

Post-Retirement Benefits

Schedule of the plan's funded status and amounts recognized in the Company's accompanying consolidated financial statements

	December 31,
(Dollars in thousands)	2017		2016		2015
Change in benefit obligation:
Benefit obligation at beginning of year	$	2,447	$	2,092	$	2,331
Interest cost		81		74		77
Participants’ contributions		—		—		—
Actuarial (gain) loss		126		546		(105)
Benefits paid		(274)		(280)		(233)
Less: Federal subsidy on benefits paid		12		15		22
Benefit obligation at end of year		2,392		2,447		2,092
Change in plan assets:
Fair value of plan assets at beginning of year		—		—		—
Employer contribution		274		280		233
Participants’ contributions		—		—		—
Benefits paid		(274)		(280)		(233)
Fair value of plan assets at end of year		—		—		—
Funded status	$	(2,392)	$	(2,447)	$	(2,092)

Schedule of weighted average assumptions used to determine benefit obligations and net periodic benefit cost

	Year Ended December 31,
	2017		2016		2015
Weighted-average assumptions used to determine benefit obligation at December 31:
Discount rate	3.20	%	3.50	%	3.70	%
Weighted-average assumptions used to determine net periodic benefit cost for years ended December 31:
Discount rate	3.50	%	3.70	%	3.45	%
Assumed health care cost trend rates at December 31:
Health care cost trend rate assumed for next year	5.00	%	5.00	%	6.25	%

Schedule of components of net periodic benefit cost and other amounts recognized in other comprehensive income

	Year Ended December 31,
(Dollars in thousands)	2017		2016		2015
Interest cost	$	81	$	74	$	77
Recognized net actuarial loss		147		95		115
Net periodic benefit cost		228		169		192
Net (gain) loss		126		546		(106)
Amortization of loss		(147)		(95)		(115)
Total amount recognized in other comprehensive income		(21)		451		(221)
Total recognized in net periodic benefit cost and other comprehensive income	$	207	$	620	$	(29)

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

	One-Percentage Point
(Dollars in thousands)	Increase		Decrease
Effect on aggregate service and interest cost	$	6	$	(6)
Effect on postretirement benefit obligation		166		(150)

Schedule of estimated future benefit payments (including expected future service as appropriate)

Estimated future benefit payments (including expected future service as appropriate):

(Dollars in thousands)
2018	$	241
2019		236
2020		230
2021		222
2022		213
2023-2027		894
	$	2,036