Retirement Benefit Plans (Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Defined Benefit Plan Disclosure [Line Items]
Service cost			$ 9	$ 9
Interest cost			954	954
Expected return on plan assets			(1,416)	(1,362)
Amortization of prior service cost			0	0
Amortization of net loss			486	99
Net periodic benefit cost	$ 11	$ (100)	33	(300)
Hourly Employees’ Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost			6	6
Interest cost			303	315
Expected return on plan assets			(495)	(477)
Amortization of prior service cost			0	0
Amortization of net loss			186	54
Net periodic benefit cost			0	(102)
Employees’ Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost			3	3
Interest cost			651	639
Expected return on plan assets			(921)	(885)
Amortization of prior service cost			0	0
Amortization of net loss			300	45
Net periodic benefit cost			$ 33	$ (198)