Retirement Benefit Plans (Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3	$ 3
Interest cost	322	318
Expected return on plan assets	(461)	(472)
Amortization of net loss	181	162
Net periodic benefit cost	45	11
Hourly Employees’ Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	2
Interest cost	100	101
Expected return on plan assets	(162)	(165)
Amortization of net loss	71	62
Net periodic benefit cost	11	0
Employees’ Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1
Interest cost	222	217
Expected return on plan assets	(299)	(307)
Amortization of net loss	110	100
Net periodic benefit cost	$ 34	$ 11