Employee Benefit, Retirement, and Deferred Compensation Plans (Tables) - U.S. Cash Balance Plan [Member]

12 Months Ended

Dec. 31, 2016

Defined Benefit Plan Disclosure [Line Items]

Summary of Changes in Total Benefit Obligation and Fair Value of Assets and Funded Status

The changes in the total benefit obligation and in the fair value of assets and the funded status of the U.S. Cash Balance Plan are as follows:

	Year Ended December 31,
(Dollars in thousands)	2016			2015
Change in benefit obligations:
Benefit obligation — beginning of period	$	32,172		$	33,929
Interest on liabilities	1,289			1,290
Benefits paid	(1,139		)	(1,339		)
Actuarial loss (gain)	62			(1,708		)
Benefit obligation — end of period	$	32,384		$	32,172
Change in fair value of plan assets:
Fair value of plan assets — beginning of period	22,910			23,691
Return on plan assets	1,558			(329		)
Employer contributions	788			887
Benefits paid	(1,139		)	(1,339		)
Fair value of plan assets — end of period	$	24,117		$	22,910
Unfunded status — end of period	$	8,267		$	9,262

Significant Weighted-Average Assumptions Adopted in Measuring Benefit Obligations and Net Periodic Pension Costs

The significant weighted-average assumptions adopted in measuring the benefit obligations and net periodic pension costs are as follows:

	Year Ended December 31,
	2016		2015		2014
Discount rate:
Net periodic pension cost	4.15	%	3.84	%	4.49	%
Pension obligation	3.97		4.15		3.98
Expected return on plan assets	6.00		7.00		7.00

Components of Net Periodic Pension Cost

Components of net periodic pension cost of the U.S. Cash Balance Plan are as follows:

	Year Ended December 31,
(Dollars in thousands)	2016			2015			2014
Interest cost	$	1,289		$	1,290		$	1,345
Amortization of net actuarial loss	132			134			34
Expected return on plan assets	(1,342		)	(1,630		)	(1,621		)
Net settlement loss	—			—			609
Net periodic pension cost	$	79		$	(206	)	$	367

Summary of Estimated Future Benefit Payments

The estimated future benefit payments in the next five years and the five years thereafter in aggregate are as follows (dollars in thousands):

Year Ending December 31,	Benefit Payments
2017	$	1,024
2018	1,432
2019	1,160
2020	1,250
2021	1,334
2022–2026	$	7,960

Fair Value of Plan's Assets by Asset Categories

The fair value of the U.S. Cash Balance Plan’s assets by asset categories is as follows:

(Dollars in thousands)	Fair Value Measurements at December 31, 2016
Asset Category	Level 1		Level 2		Level 3		Total
Fixed-income securities	$	11,625	$	—	$	—	$	11,625
U.S. equity securities	8,731		—		—		8,731
International equity securities	2,822		—		—		2,822
Cash	409		—		—		409
Other	530		—		—		530
Total	$	24,117	$	—	$	—	$	24,117

(Dollars in thousands)	Fair Value Measurements at December 31, 2015
Asset Category	Level 1		Level 2		Level 3		Total
Fixed-income securities	$	11,435	$	—	$	—	$	11,435
U.S. equity securities	8,058		—		—		8,058
International equity securities	2,481		—		—		2,481
Cash	426		—		—		426
Other	510		—		—		510
Total	$	22,910	$	—	$	—	$	22,910

Summary of Target Allocation Percentages of Plan Assets

The range of target allocation percentages of plan assets of the U.S. Cash Balance Plan is as follows:

	Minimum		Maximum		Target
U.S. equity securities	33	%	43	%	38	%
International equity securities	7		17		12
Fixed-income securities	40		50		45
Other	—		10		5
					100	%