Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended			12 Months Ended
	Jun. 30, 2013 SERP	Jun. 30, 2012 SERP	Jun. 30, 2013 SERP	Jun. 30, 2012 SERP	Jun. 30, 2013 Split-Dollar Life Insurance Benefit Plan	Dec. 31, 2012 Split-Dollar Life Insurance Benefit Plan
Benefit plans
Plan assets associated with the plan	$ 0		$ 0
Components of net periodic benefit cost:
Service cost	302	294	606	588
Interest cost	196	193	392	386	89	185
Amortization of prior service cost		7		14
Amortization of net actuarial loss	75	63	146	126
Net periodic benefit cost	573	557	1,144	1,114
Change in projected benefit obligation
Projected benefit obligation at beginning of year					4,717	4,525
Actuarial gain					2	7
Projected benefit obligation at end of period					$ 4,808	$ 4,717