Employee Post-Retirement 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
Components of net periodic benefit cost
Service cost	$ 150	$ 127	$ 450	$ 381
Interest cost	188	200	564	600
Expected return on plan assets	0	0	0	0
Amortization of transition obligation	15	15	45	45
Amortization of prior service cost	(19)	(14)	(57)	(42)
Recognized net actuarial loss	135	107	405	321
Net periodic benefit cost	469	435	1,407	1,305
Employer's contribution for current premium:
Defined Benefit Plan Payments Made By Employer				258
Expected contributions for remainder of current year	110		110
Estimated Employer Contributions For Current Fiscal Year			$ 368