Retirement Benefit Plans (Schedule of Changes in Plan Assets, Changes in Projected Benefit Obligation, Rate Assumptions, and Components of Net Periodic Benefit Costs) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Change in fair value of plan assets
Fair value of plan assets at end of year	$ 25,274	$ 21,838
Pension Plans, Defined Benefit
Change in projected benefit obligation
Benefit obligation at beginning of year	31,709	29,692
Service cost	16	14
Interest cost	1,131	1,199
Liability actuarial (gain)/loss	(3,680)	2,168
Benefits paid	(1,364)	(1,364)
Benefit obligation at end of year	27,812	31,709
Change in fair value of plan assets
Fair value of plan assets at beginning of year	21,838	18,900
Return on plan assets	3,226	2,659
Employer contributions	1,574	1,643
Fair value of plan assets at end of year	25,274	21,838
Underfunded status – December 31, 2012	(2,538)	(9,871)
Accumulated benefit obligation – December 31, 2013	27,812	31,709
Supplemental Employee Retirement Plans, Defined Benefit
Change in projected benefit obligation
Benefit obligation at beginning of year	3,057	2,584
Service cost	114	101
Interest cost	102	104
Liability actuarial (gain)/loss	(252)	268
Plan Amendments	0	0
Benefit obligation at end of year	3,021	3,057
Hourly Employees’ Pension Plan | Pension Plans, Defined Benefit
Change in projected benefit obligation
Benefit obligation at beginning of year	10,786	10,454
Service cost	11	10
Interest cost	371	411
Liability actuarial (gain)/loss	(1,060)	549
Benefits paid	(631)	(638)
Benefit obligation at end of year	9,477	10,786
Change in fair value of plan assets
Fair value of plan assets at beginning of year	7,690	6,663
Return on plan assets	1,136	937
Employer contributions	678	728
Fair value of plan assets at end of year	8,873	7,690
Underfunded status – December 31, 2012	(604)	(3,096)
Accumulated benefit obligation – December 31, 2013	9,477	10,786
Employees’ Retirement Plan | Pension Plans, Defined Benefit
Change in projected benefit obligation
Benefit obligation at beginning of year	20,923	19,238
Service cost	5	4
Interest cost	760	788
Liability actuarial (gain)/loss	(2,620)	1,619
Benefits paid	(733)	(726)
Benefit obligation at end of year	18,335	20,923
Change in fair value of plan assets
Fair value of plan assets at beginning of year	14,148	12,237
Return on plan assets	2,090	1,722
Employer contributions	896	915
Fair value of plan assets at end of year	16,401	14,148
Underfunded status – December 31, 2012	(1,934)	(6,775)
Accumulated benefit obligation – December 31, 2013	$ 18,335	$ 20,923