Pensions and Other Postretirement Benefit Plans (Schedule of Funded Status of Plans) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 173,434	$ 304,658	$ 262,376
Benefit obligation	218,538	405,880	374,115
Funded status	(45,104)	(101,222)
Noncurrent asset	7,034	7,779
Current liability	(2,318)	(3,576)
Noncurrent liability	(49,820)	(105,425)
Net amount recognized	(45,104)	(101,222)
Net actuarial loss	84,784	164,246
Prior service cost/(credit)	405	432
Transition obligation	70	138
Net amount recognized	85,259	164,816
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Benefit obligation	84,368	79,009	72,137
Funded status	(84,368)	(79,009)
Noncurrent asset
Current liability	(5,547)	(5,949)
Noncurrent liability	(78,821)	(73,060)
Net amount recognized	(84,368)	(79,009)
Net actuarial loss	57,966	54,835
Prior service cost/(credit)	(40,329)	(43,995)
Transition obligation
Net amount recognized	$ 17,637	$ 10,840