Investments (Schedule Of Available-For-Sale Securities Investments Results)(Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale equity securities, amoritzed cost	$ 7,900,000	$ 7,900,000
Available-for-sales securities, gross unrealized gains	20,260,000	16,860,000
Available-for-sale securities, gross unrealized losses	0	0
Available-for-sale securities gross, Fair Value	28,160,000	24,760,000
Deferred taxes on unrealized holdings gains	8,104,000	6,744,000
Unrealized gains recorded in equity, net of deferred tax	12,156,000	10,116,000
Cement Industry [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale equity securities, amoritzed cost	2,940,000	2,940,000
Available-for-sales securities, gross unrealized gains	12,540,000	9,730,000
Available-for-sale securities, gross unrealized losses	0	0
Available-for-sale securities gross, Fair Value	15,480,000	12,670,000
General Building Materials Industry [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale equity securities, amoritzed cost	3,600,000	3,600,000
Available-for-sales securities, gross unrealized gains	3,740,000	2,970,000
Available-for-sale securities, gross unrealized losses	0	0
Available-for-sale securities gross, Fair Value	7,340,000	6,570,000
Oil And Gas Refining And Marketing Industry [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale equity securities, amoritzed cost	340,000	340,000
Available-for-sales securities, gross unrealized gains	3,970,000	4,090,000
Available-for-sale securities, gross unrealized losses	0	0
Available-for-sale securities gross, Fair Value	4,310,000	4,430,000
Residential Construction Industry [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale equity securities, amoritzed cost	1,020,000	1,020,000
Available-for-sales securities, gross unrealized gains	10,000	70,000
Available-for-sale securities, gross unrealized losses	0	0
Available-for-sale securities gross, Fair Value	$ 1,030,000	$ 1,090,000