Unaudited Condensed Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Income Statement [Abstract]
Revenues	$ 177,413	$ 196,052
Cost of sales	141,242	149,791
Gross profit	36,171	46,261
Earnings of unconsolidated mines	12,438	12,098
Operating expenses
Selling, general and administrative expenses	48,429	50,296
Amortization of intangible assets	765	1,041
Operating Expenses	49,194	51,337
Operating profit (loss)	(585)	7,022
Other expense (income)
Interest expense	1,454	1,304
Income from other unconsolidated affiliates	(388)	(391)
Closed mine obligations	316	405
Other, net, including interest income	122	(133)
Other (income) expense	1,504	1,185
Income (loss) before income tax provision (benefit)	(2,089)	5,837
Income tax provision (benefit)	(565)	1,415
Net income (loss)	$ (1,524)	$ 4,422
Earnings Per Share [Abstract]
Basic earnings (loss) per share (in dollars per share)	$ (0.19)	$ 0.53
Diluted earnings (loss) per share (in dollars per share)	$ (0.19)	$ 0.53
Dividends per share (in dollars per share)	$ 0.25	$ 0.25
Basic weighted average shares outstanding	7,848	8,360
Diluted weighted average shares outstanding	7,860	8,399