Pensions and Other Postretirement Benefit Plans (Schedule of Pension Plans with Projected Benefit Obligation in Excess of Plan Assets and for Pension Plans with an Accumulated Benefit Obligation in Excess of Plan Assets) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Plans with projected benefit obligation in excess of plan assets:
Projected benefit obligation	$ 183,765	$ 376,595
Accumulated benefit obligation	169,396	363,228
Fair value of plan assets	131,626	267,594
Plans with accumulated benefit obligation in excess of plan assets:
Projected benefit obligation	136,329	376,595
Accumulated benefit obligation	132,396	363,228
Fair value of plan assets	$ 86,835	$ 267,594