Consolidated Statements Of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Net income (loss)	$ 30,211	$ 12,014	$ (9,424)
Other comprehensive income (loss), net of tax:
Defined benefit pension plans	(75,807)	41,656	34,857
Other postretirement benefit plans	(8,979)	(6,433)	(6,972)
Total other comprehensive income (loss), net	(84,786)	35,223	27,885
Comprehensive income (loss)	(54,575)	47,237	18,461
Accumulated other comprehensive income (loss), net of tax:
Balance at beginning of year	(97,307)	(132,530)	(160,415)
Total other comprehensive income (loss), net	(84,786)	35,223	27,885
Balance at end of year	(182,093)	(97,307)	(132,530)
Defined Benefit Pension Plans [Member]
Accumulated other comprehensive income (loss), net of tax:
Balance at beginning of year	(116,745)	(158,401)	(193,258)
Net actuarial gain (loss) arising during year	(80,963)	31,388	21,611
Amortization of prior service cost / (credit)	744	761	805
Amortization of net actuarial losses	4,412	9,507	12,441
Balance at end of year	(192,552)	(116,745)	(158,401)
Defined Benefit OPEB Plans [Member]
Accumulated other comprehensive income (loss), net of tax:
Balance at beginning of year	19,438	25,871	32,843
Plan amendment			(49)
Net actuarial gain (loss) arising during year	(4,025)	(1,581)	(2,032)
Amortization of prior service cost / (credit)	(9,765)	(9,990)	(10,473)
Amortization of net actuarial losses	4,811	5,138	5,582
Balance at end of year	$ 10,459	$ 19,438	$ 25,871