Employee Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Pension Benefits [Member]
Components of Net Periodic Benefit Cost
Service cost	$ 274	$ 211	$ 822	$ 633
Interest	323	355	970	1,065
Expected return on plan assets	(410)	(399)	(1,230)	(1,197)
Recognized prior service cost (benefit)	(26)	(26)	(78)	(78)
Recognized net actuarial losses	184	123	553	370
Net periodic benefit cost	345	264	1,037	793
Supplemental Insurance/ Retirement Plan [Member]
Components of Net Periodic Benefit Cost
Service cost	355	170	1,066	510
Interest	231	233	693	699
Expected return on plan assets
Recognized prior service cost (benefit)	29	28	87	84
Recognized net actuarial losses	84	32	252	97
Net periodic benefit cost	$ 699	$ 463	$ 2,098	$ 1,390