Business Segments (Net Sales By Product Line) (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Net Sales	$ 463,985	$ 443,709	$ 1,196,931	$ 1,182,054
Aggregates [Member]
Net Sales	379,325	376,554	963,991	986,038
Asphalt [Member]
Net Sales	13,095	9,833	38,062	29,014
Ready Mixed Concrete [Member]
Net Sales	9,750	7,056	22,691	19,558
Road Paving [Member]
Net Sales	10,017	6,575	19,425	12,602
Other Product Line [Member]
Net Sales	1,456	1,428	3,678	2,964
Total Aggregates Business [Member]
Net Sales	413,643	401,446	1,047,847	1,050,176
Magnesia-Based Chemicals [Member]
Net Sales	36,064	29,290	105,369	89,287
Dolomitic Lime [Member]
Net Sales	13,861	12,457	42,743	41,386
Others [Member]
Net Sales	417	516	972	1,205
Specialty Products [Member]
Net Sales	$ 50,342	$ 42,263	$ 149,084	$ 131,878