Retirement Plans (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Employees' Pension Plan [Member]
Net Periodic Benefit Cost [Line Items]
Service Cost	$ 353		$ 376	$ 705	$ 753
Interest Cost	407		268	802	598
Expected Return on Plan Assets	(808)		(723)	(1,615)	(1,445)
Amortization of Prior Service (Credit) Cost	(21)		(11)	(42)	(22)
Amortization of Net Loss	139		86	278	172
Net Periodic Benefit Cost	70		(4)	128	56
Contributions to Retirement Benefits Plans	0		0	0	0
Estimated Future Contributions in the Current Fiscal Year		$ 0
Select Executive Retirement Plan [Member]
Net Periodic Benefit Cost [Line Items]
Service Cost	3		0	5	0
Interest Cost	71		48	121	109
Expected Return on Plan Assets	0		0	0	0
Amortization of Prior Service (Credit) Cost	15		18	29	36
Amortization of Net Loss	30		22	61	45
Net Periodic Benefit Cost	119		88	216	190
Contributions to Retirement Benefits Plans	159		118	274	237
Estimated Future Contributions in the Current Fiscal Year		548
Post-Retirement Benefit Plans [Member]
Net Periodic Benefit Cost [Line Items]
Service Cost	43		53	87	106
Interest Cost	159		62	217	172
Expected Return on Plan Assets	0		0	0	0
Amortization of Prior Service (Credit) Cost	(8)		(28)	(16)	(57)
Amortization of Net Loss	24		6	48	13
Net Periodic Benefit Cost	218		93	336	234
Contributions to Retirement Benefits Plans	$ 78		$ 86	$ 125	$ 228
Estimated Future Contributions in the Current Fiscal Year		$ 250