Retirement Plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Employees' Pension Plan [Member]
Net Periodic Benefit Cost [Line Items]
Service Cost	$ 376	$ 353	$ 752	$ 705
Interest Cost	424	407	844	802
Expected Return on Plan Assets	(828)	(808)	(1,656)	(1,615)
Amortization of Prior Service (Credit) Cost	(15)	(21)	(30)	(42)
Amortization of Net Loss	138	139	278	278
Net Periodic Benefit Cost	95	70	188	128
Contributions to Retirement Benefits Plans	0	0	0	0
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year			0
Select Executive Retirement Plan [Member]
Net Periodic Benefit Cost [Line Items]
Service Cost	8	3	16	5
Interest Cost	48	71	106	121
Expected Return on Plan Assets	0	0	0	0
Amortization of Prior Service (Credit) Cost	14	15	29	29
Amortization of Net Loss	28	30	56	61
Net Periodic Benefit Cost	98	119	207	216
Contributions to Retirement Benefits Plans	112	159	219	274
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year			224
Post-Retirement Benefit Plans [Member]
Net Periodic Benefit Cost [Line Items]
Service Cost	63	43	125	87
Interest Cost	15	159	96	217
Expected Return on Plan Assets	0	0	0	0
Amortization of Prior Service (Credit) Cost	(3)	(8)	(6)	(16)
Amortization of Net Loss	0	24	0	48
Net Periodic Benefit Cost	75	218	215	336
Contributions to Retirement Benefits Plans	$ 72	$ 78	150	$ 125
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year			$ 144