Retirement Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Contributions to Pension Plans	$ (111)	$ (80)
Employees' Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	367	340
Interest Cost	353	404
Expected Return on Plan Assets	(716)	(755)
Amortization of Prior Service Cost (Credit)	9	10
Amortization of Net Loss	312	310
Net Periodic Benefit Cost	325	309
Contributions to Pension Plans	0	0
Estimated Future Contributions in the Current Fiscal Year			0
Select Executive Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	22	19
Interest Cost	38	51
Expected Return on Plan Assets	0	0
Amortization of Prior Service Cost (Credit)	20	11
Amortization of Net Loss	38	35
Net Periodic Benefit Cost	118	116
Contributions to Pension Plans	111	80
Estimated Future Contributions in the Current Fiscal Year			346
Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	51	45
Interest Cost	81	88
Expected Return on Plan Assets	0	0
Amortization of Prior Service Cost (Credit)	(29)	(28)
Amortization of Net Loss	41	33
Net Periodic Benefit Cost	144	138
Contributions to Pension Plans	81	74
Estimated Future Contributions in the Current Fiscal Year			$ 413