Changes in Goodwill (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2015 USD ($)
Goodwill [Line Items]
Balance at beginning of period	$ 2,068,799
Adjustments to purchase price allocations	(3,096)
Acquisitions	655
Divestitures	(714)
Balance at end of period	2,065,644
Mid-America Group
Goodwill [Line Items]
Balance at beginning of period	282,117
Divestitures	(714)
Balance at end of period	281,403
Southeast Group
Goodwill [Line Items]
Balance at beginning of period	50,346
Balance at end of period	50,346
West Group
Goodwill [Line Items]
Balance at beginning of period	852,436
Adjustments to purchase price allocations	15,538
Acquisitions	655
Balance at end of period	868,629
Cement
Goodwill [Line Items]
Balance at beginning of period	883,900
Adjustments to purchase price allocations	(18,634)
Balance at end of period	$ 865,266