Unaudited Condensed Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Income Statement [Abstract]
Revenues	$ 196,017	$ 171,435	$ 392,069	$ 345,114
Cost of sales	148,387	128,138	298,178	256,298
Gross profit	47,630	43,297	93,891	88,816
Earnings of unconsolidated mines	10,281	10,579	22,379	22,585
Operating expenses
Selling, general and administrative expenses	48,484	48,125	98,434	96,932
Amortization of intangible assets	619	464	1,660	1,073
(Gain) loss on sale of assets	5	(2,314)	351	(2,273)
Operating Expenses	49,108	46,275	100,445	95,732
Operating profit	8,803	7,601	15,825	15,669
Other (income) expense
Interest expense	1,148	1,504	2,452	3,211
Income from other unconsolidated affiliates	(336)	(432)	(727)	(783)
Closed mine obligations	272	860	677	1,194
Other net, including interest income	476	839	343	467
Other (income) expense	1,560	2,771	2,745	4,089
Income from continuing operations before income tax provision	7,243	4,830	13,080	11,580
Income tax provision	2,096	1,387	3,511	3,425
Income from continuing operations, net of tax	5,147	3,443	9,569	8,155
Income from discontinued operations, net of tax expense of $2,237 and $8,752 in the three and six months ended June 30, 2012, respectively	0	18,269	0	38,807
Net income	$ 5,147	$ 21,712	$ 9,569	$ 46,962
Basic Earnings per Share:
Continuing operations	$ 0.63	$ 0.42	$ 1.16	$ 0.97
Discontinued operations	$ 0.00	$ 2.18	$ 0.00	$ 4.64
Basic earnings per share	$ 0.63	$ 2.60	$ 1.16	$ 5.61
Diluted Earnings per Share:
Continuing operations	$ 0.63	$ 0.42	$ 1.16	$ 0.97
Discontinued operations	$ 0.00	$ 2.18	$ 0.00	$ 4.63
Diluted earnings per share	$ 0.63	$ 2.60	$ 1.16	$ 5.60
Dividends per share	$ 0.25	$ 0.5475	$ 0.5	$ 1.08
Basic Weighted Average Shares Outstanding	8,179	8,388	8,259	8,383
Diluted Weighted Average Shares Outstanding	8,184	8,400	8,284	8,397