Pension and Other Post-Retirement Benefit Plans (Defined Contribution Plan Expense) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of Defined Contribution Plans [Line Items]
Defined contribution plan expense	$ 5,300	$ 4,938	$ 4,637
Capital accumulation plans [Member]
Schedule of Defined Contribution Plans [Line Items]
Defined contribution plan expense	5,300	4,938	4,527
Profit sharing plans [Member]
Schedule of Defined Contribution Plans [Line Items]
Defined contribution plan expense	$ 0	$ 0	$ 110