Business Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013 segment	Dec. 31, 2012	Dec. 31, 2011
Business Segments
Number of business segments									2
Business segments
Revenues	$ 30,109	$ 36,899	$ 35,172	$ 31,585	$ 31,883	$ 34,116	$ 36,498	$ 36,028	$ 133,765	$ 138,525	$ 142,582
Depreciation, depletion and amortization									14,291	14,850	13,597
Gross profit	6,435	9,110	8,964	6,291	8,123	7,759	8,353	9,203	30,800	33,438	41,349
Identifiable assets, at year end	187,526				174,246				187,526	174,246	203,073
Capital expenditures									8,921	8,292	9,413
Lime and limestone operations
Business segments
Revenues									128,003	131,404	129,704
Depreciation, depletion and amortization									13,336	13,559	12,195
Gross profit									27,913	29,499	32,142
Identifiable assets, at year end	124,839				130,059				124,839	130,059	133,487
Capital expenditures									8,863	8,211	7,696
Natural gas interests
Business segments
Revenues									5,762	7,121	12,878
Depreciation, depletion and amortization									955	1,291	1,402
Gross profit									2,887	3,939	9,207
Identifiable assets, at year end	10,910				11,943				10,910	11,943	13,789
Capital expenditures									58	81	1,717
Unallocated corporate assets and cash items
Business segments
Identifiable assets, at year end	$ 51,777				$ 32,244				$ 51,777	$ 32,244	$ 55,797