Employee Benefit and Deferred Compensation Plans (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]
Plan expense for noncontributory benefit pension plan and post-retirement health and life plans
Service cost
Interest cost	216	228	646	686
Expected return on plan assets	(298)	(307)	(894)	(923)
Prior service cost recognized
Recognized actuarial loss	88	76	266	228
Recognized curtailment loss
Net periodic benefit cost	6	(3)	18	(9)
Other Benefits [Member]
Plan expense for noncontributory benefit pension plan and post-retirement health and life plans
Service cost	6	9	18	27
Interest cost	16	21	48	59
Expected return on plan assets
Prior service cost recognized
Recognized actuarial loss	18	34	54	106
Recognized curtailment loss
Net periodic benefit cost	$ 40	$ 64	$ 120	$ 192