Retirement Benefit Plans (Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Defined Benefit Plan Disclosure [Line Items]
Service cost			$ 6	$ 6
Interest cost			636	636
Expected return on plan assets			(944)	(908)
Amortization of prior service cost			0	0
Amortization of net (gain)/loss			324	66
Net periodic benefit cost	$ 11	$ (100)	22	(200)
Hourly Employees’ Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost			4	4
Interest cost			202	210
Expected return on plan assets			(330)	(318)
Amortization of prior service cost			0	0
Amortization of net (gain)/loss			124	36
Net periodic benefit cost			0	(68)
Employees’ Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost			2	2
Interest cost			434	426
Expected return on plan assets			(614)	(590)
Amortization of prior service cost			0	0
Amortization of net (gain)/loss			200	30
Net periodic benefit cost			$ 22	$ (132)