Retirement Benefit Plans (Schedule of Assumptions Used) (Details)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension expense, rate of compensation increase	3.00%	3.00%
Supplemental Employee Retirement Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.37%	4.04%
Composite rate of compensation increase	3.00%	3.00%
Net periodic pension expense, discount rate	4.04%	5.28%
Hourly Employees’ Pension Plan | Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.55%	4.06%
Net periodic pension expense, discount rate	4.06%	5.12%
Net periodic pension expense, Long-term rate of return on plan assets	7.75%	7.75%
Employees’ Retirement Plan | Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.70%	4.18%
Net periodic pension expense, discount rate	4.18%	5.30%
Net periodic pension expense, Long-term rate of return on plan assets	7.75%	7.75%