Benefit Obligations (Details 7) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Accumulated other comprehensive loss
Accumulated other comprehensive loss, after tax	$ 578,757	$ 372,376
Pension Benefits [Member]
Accumulated other comprehensive loss
Net prior service cost	242	278
Net actuarial loss	527,045	334,809
Transition asset	(157)	(175)
Accumulated other comprehensive loss	527,130	334,912
Tax on prior actuarial gains	23,813	23,813
Accumulated other comprehensive loss, after tax	550,943	358,725	319,507	292,951
Post-retirement Benefits [Member]
Accumulated other comprehensive loss
Net prior service cost	0	0
Net actuarial loss	24,788	10,625
Transition asset	0	0
Accumulated other comprehensive loss	24,788	10,625
Tax on prior actuarial gains	3,026	3,026
Accumulated other comprehensive loss, after tax	$ 27,814	$ 13,651	$ 12,694	$ 13,883

The total of net gain (loss), prior service cost (credit), and transition assets (obligations), as well as minimum pension liability if still remaining, included in accumulated other comprehensive income associated with a defined benefit pension or other postretirement plan(s) because they have yet to be recognized as components of net periodic benefit cost.

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+ Details

- Definition

The pretax net amount of gains and losses that are not yet recognized as a component of net periodic benefit cost, and that are recognized as increases or decreases in other comprehensive income as they arise. Gains and losses are due to changes in the value of either the benefit obligation or the plan assets resulting from experience different from that assumed or from a change in an actuarial assumption, or the consequence of a decision to temporarily deviate from the substantive plan.

+ References+ Details

- Definition

Amount related to the pretax cost of benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation, which has not yet been recognized as components of net periodic benefit cost.

+ References

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- Definition

Of the original amount of transition assets as of the date FAS 87 or 106 was initially applied, (a) the fair value of plan assets plus any recognized accrued pension or other postretirement benefit cost or less any recognized prepaid pension or other postretirement benefit cost in excess of (b) the benefit obligation, the portion of which has yet to be recognized as components of net periodic benefit cost. Of the original amount of transition obligations as of the date FAS 87 or 106 was initially applied, (a) the benefit obligation in excess of (b) the fair value of plan assets plus any recognized accrued pension or other postretirement benefit cost or less any recognized prepaid pension or other postretirement benefit cost, the portion of which has yet to be recognized as components of net periodic benefit cost. This amount is pretax.

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-Glossary Transition Obligation

-URI http://asc.fasb.org/extlink&oid=6749492

+ Details

- Definition

Tax effect of the change in accumulated other comprehensive income, that is, the tax effect on items included in other comprehensive income during the period that is attributable to the parent entity. While for technical reasons this element has no balance attribute, the default assumption is a credit balance consistent with its label.

+ References

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