Employee Benefits (Postretirement Benefits Other Than Pension Expenses) (Details) (Postretirement Benefits Plan [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost for benefits earned	$ 341	$ 258
Interest cost on projected benefit obligation	1,447	1,454
Net amortization and deferrals	(361)	(672)
Net periodic benefit cost	$ 1,427	$ 1,040