Benefit Plans (Details 6) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Benefit Plans
Accumulated benefit obligation	$ 260,100	$ 244,200
Unfunded Retirement Plans
Benefit Plans
Projected benefit obligation	14,647	30,113
Accumulated benefit obligation	$ 14,647	$ 26,588

For defined benefit pension plans, the actuarial present value of benefits (whether vested or nonvested) attributed by the pension benefit formula to employee service rendered before a specified date and based on employee service and compensation (if applicable) before that date. The accumulated benefit obligation differs from the projected benefit obligation in that it includes no assumption about future compensation levels. For plans with flat-benefit or nonpay-related pension benefit formulas, the accumulated benefit obligation and the projected benefit obligation are the same.

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If aggregate disclosures are presented, the aggregate projected benefit obligation for pension plans with accumulated benefit obligations in excess of plan assets as of the measurement date of each statement of financial position presented.

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