Level 4 Retirement and Benefit Plans (Details) (USD $)	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Net periodic benefit cost [Abstract]
Service cost	$ 671,000	$ 1,169,000
Interest cost	4,642,000	4,843,000
Expected return on plan assets	(4,866,000)	(4,844,000)
Amortization of actuarial loss	2,256,000	2,026,000
Amortization of prior service costs	23,000	41,000
Net periodic benefit cost	2,726,000	3,235,000
Pension contributions [Abstract]
Pension contributions	9,663,000	3,941,000
Estimated remaining 2013 contributions	$ 1,000,000

The amount of gains or losses recognized in net periodic benefit cost.

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- Definition

The amount of the prior service cost or credit recognized in net periodic benefit cost relating to benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation.

+ References

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The employer's best estimate, as soon as it can be reasonably determined, of contributions expected to be paid to the plan in the current remaining fiscal period. Estimated contributions may be presented in the aggregate combining (1) contributions required by funding regulations or laws, (2) discretionary contributions, and (3) noncash contributions.

+ References

No definition available.

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- Definition

An amount calculated as a basis for determining the extent of delayed recognition of the effects of changes in the fair value of assets. The expected return on plan assets is determined based on the expected long-term rate of return on plan assets and the market-related value of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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- Definition

The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.

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- Definition

The total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments.

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- Definition

The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan.

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-Glossary Service Cost (Component of Net Periodic Pension Cost)

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The amount of cash or cash equivalents contributed by the entity to fund its pension plans.

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