Employee Benefit Plans Summary of Pension Plan and Postretirement Plan Net Periodic Benefit Cost (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Pension Plan [Member]
Define Benefit Plan Disclosure [Line Items]
Service cost	$ 39	[1]	$ 15	[1]
Interest cost	806		853
Expected return on plan assets	(808)		(837)
Net amortization and deferral	420		72
Net periodic benefit cost	457		103
Postretirement Plan [Member]
Define Benefit Plan Disclosure [Line Items]
Service cost	53		51
Interest cost	87		107
Expected return on plan assets	(1)		(1)
Net accretion and deferral	(91)		(91)
Net periodic benefit cost	$ 48		$ 66

[1] The net periodic benefit cost for the Corporation’s Pension Plan, as determined by consulting actuaries, consisted of the following components for the three months ended March 31: 2012 2011 (in thousands)Service cost (1)$39 $15Interest cost806 853Expected return on plan assets(808) (837)Net amortization and deferral420 72Net periodic benefit cost$457 $103 (1)The Pension Plan service cost recorded for the three months ended March 31, 2012 and 2011, respectively, was related to administrative costs associated with the plan and not due to the accrual of additional participant benefits.