Retirement Benefit Plans (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Service cost			$ 6	$ 6
Interest cost			644	636
Expected return on plan assets			(922)	(944)
Amortization of net loss			362	324
Net periodic benefit cost	$ 45	$ 11	90	22
Hourly Employees’ Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost			4	4
Interest cost			200	202
Expected return on plan assets			(324)	(330)
Amortization of net loss			142	124
Net periodic benefit cost			22	0
Employees’ Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost			2	2
Interest cost			444	434
Expected return on plan assets			(598)	(614)
Amortization of net loss			220	200
Net periodic benefit cost			$ 68	$ 22