Benefit Plans (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Component accumulated benefit obligation
Net actuarial gains	$ 612	$ 1,016
Prior service credit	1,117	690
Net of tax amount	$ 15	$ (690)	$ (670)

Net of tax amount of the benefit improvement costs resulting from a plan amendment that occurred that has not been recognized in net periodic benefit cost.

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+ Details