Retirement Benefits (Schedule of Net Benefit Costs) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Compensation and Retirement Disclosure [Abstract]
Interest cost	$ 2,191	$ 2,476	$ 2,716
Amortization of unrecognized:
Prior service costs	3,023	3,023	3,023
Net actuarial loss	8,143	2,197	1,330
Net periodic pension cost	$ 13,357	$ 7,696	$ 7,069