Retirement Plans (Tables)

12 Months Ended

Dec. 31, 2015

Retirement Plans [Abstract]

Schedule of Expected Benefit Payments [Table Text Block]

Benefit payments during the next ten years, which reflect applicable future service, are as follows:

Year Ended December 31,	Amount
(Thousands of dollars)
2016	$	1,557
2017	$	1,243
2018	$	1,463
2019	$	1,432
2020	$	1,480
Years 2021 to 2025	$	7,711

Periodic Pension Cost, Next Fiscal Year [Table Text Block]

The following is an estimate of the components of net periodic pension cost in 2016:

Estimated Year Ended December 31,	2016
(Thousands of dollars)
Service cost	$	—
Interest cost	1,216
Amortization of actuarial loss	336
Estimated 2016 net periodic pension cost	$	1,552

Schedule of Changes in Projected Benefit Obligations [Table Text Block]

The following table summarizes the changes in plan benefit obligations:

Year Ended December 31,	2015			2014
(Thousands of dollars)
Change in benefit obligation
Beginning benefit obligation	$	30,047		$	25,145
Service cost	44			84
Interest cost	1,230			1,171
Actuarial loss (gain)	(1,372		)	5,014
Benefit payments	(1,550		)	(1,367		)
Ending benefit obligation	$	28,399		$	30,047

Schedule of Defined Benefit Plans Disclosures [Table Text Block]

Year Ended December 31,	2015			2014
(Thousands of dollars)
Change in plan assets
Fair value of plan assets at beginning of year	$	—		$	—
Employer contribution	1,550			1,367
Benefit payments	(1,550		)	(1,367		)
Fair value of plan assets at end of year	$	—		$	—
Funded Status	$	(28,399	)	$	(30,047	)
Amounts recognized in the consolidated balance sheets consist of:
Accrued liabilities	(1,524		)	(1,507		)
Other non-current liabilities	(26,875		)	(28,540		)
Net amount recognized	$	(28,399	)	$	(30,047	)
Amounts recognized in accumulated other comprehensive loss consist of:
Net actuarial loss	$	6,492		$	8,399
Prior service cost	(1		)	(1		)
Net amount recognized, before tax effect	$	6,491		$	8,398
Weighted average assumptions used to determine benefit obligations:
Discount rate	4.4		%	4.2		%
Rate of compensation increase	3.0		%	3.0		%

Schedule of Net Benefit Costs [Table Text Block]

Components of net periodic pension cost are described in the following table:

Year Ended December 31,	2015			2014			2013
(Thousands of dollars)
Components of net periodic pension cost:
Service cost	$	44		$	84		$	230
Interest cost	1,230			1,171			1,159
Amortization of actuarial loss	535			328			430
Net periodic pension cost	$	1,809		$	1,583		$	1,819
Weighted average assumptions used to determine net periodic pension cost:
Discount rate	4.2		%	4.8		%	4.0		%
Rate of compensation increase	3.0		%	3.0		%	3.0		%