Consolidated Statements of Changes in Stockholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Accumulated Other Comprehensive Loss	Additional Paid-In Capital	Treasury Stock, at Cost	Accumulated Deficit
Balance at Dec. 31, 2011	$ 58,998	$ 127	$ (188,389)	$ 555,746		$ (308,486)
Balance (in shares) at Dec. 31, 2011		12,646
Stockholders' Equity Line Items
Amortization, issuance, and forfeitures of restricted stock grants (in shares)		494
Amortization, issuance and forfeitures of restricted stock grants	4,228	4		4,224
Unrealized gain (loss) on available-for-sale investments, net of tax	(8,894)		(8,894)
Changes in pension liability and other post-retirement benefit obligations, net of tax	(29,247)		(29,247)
Foreign currency translation adjustments	362		362
Net income	26,481					26,481
Balance at Dec. 31, 2012	51,928	131	(226,168)	559,970		(282,005)
Balance (in shares) at Dec. 31, 2012		13,140
Stockholders' Equity Line Items
Amortization, issuance, and forfeitures of restricted stock grants (in shares)		304
Amortization, issuance and forfeitures of restricted stock grants	5,474	3		5,471
Unrealized gain (loss) on available-for-sale investments, net of tax	1,710		1,710
Reclassification of unrealized loss on available-for-sale investments, net of tax	2,362		2,362
Changes in pension liability and other post-retirement benefit obligations, net of tax	42,675		42,675
Foreign currency translation adjustments	(2,510)		(2,510)
Purchases of treasury stock	(9,796)				(9,796)
Net income	42,029					42,029
Balance at Dec. 31, 2013	133,872	134	(181,931)	565,441	(9,796)	(239,976)
Balance (in shares) at Dec. 31, 2013		13,444
Stockholders' Equity Line Items
Amortization, issuance, and forfeitures of restricted stock grants (in shares)		136
Amortization, issuance and forfeitures of restricted stock grants	4,817	2		4,815
Changes in pension liability and other post-retirement benefit obligations, net of tax	(51,963)		(51,963)
Foreign currency translation adjustments	(1,928)		(1,928)
Purchases of treasury stock	(60,579)				(60,579)
Net income	25,170					25,170
Balance at Dec. 31, 2014	$ 49,389	$ 136	$ (235,822)	$ 570,256	$ (70,375)	$ (214,806)
Balance (in shares) at Dec. 31, 2014		13,580