CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (unaudited) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (27,024)	$ 138,970	$ 309,086
Other comprehensive income (loss), net of tax:
Net actuarial pension (loss) gain, net of income tax of $6,811, $242 and $3,709	10,755	379	(5,795)
Net actuarial pension loss amortization, net of income tax of $790, $1,062 and $704	1,247	1,656	1,099
Prior service cost (credit) amortization, net of income tax of $604, $607 and $607	(951)	(948)	(948)
Pension settlement (loss), net of income tax of $17, $309 and $470	25	483	734
Unrealized gains (losses) on available-for-sale securities, net of income tax of $0, $0 and $0	0	(21)	(60)
Other comprehensive income (loss), net of tax	11,076	1,549	(4,970)
Comprehensive income (loss)	$ (15,948)	$ 140,519	$ 304,116