Changes in Goodwill (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013
Goodwill
Balance at beginning of period	$ 616,621	$ 616,204	$ 616,634
Acquisitions	1,457,043	444
Amounts allocated to divestitures	(30,344)
Adjustments to purchase price allocations		(27)
Balance at end of period	2,043,320	616,621	616,634
Mid-America Group
Goodwill
Balance at beginning of period	263,967	263,868
Organizational changes	18,150
Acquisitions		99
Balance at end of period	282,117	263,967
Southeast Group
Goodwill
Balance at beginning of period	50,346	50,001
Acquisitions		345
Balance at end of period	50,346	50,346
West Group
Goodwill
Balance at beginning of period	302,308	302,335
Organizational changes	(18,150)
Acquisitions	614,224
Amounts allocated to divestitures	(30,344)
Adjustments to purchase price allocations		(27)
Balance at end of period	868,038	302,308
Cement
Goodwill
Acquisitions	842,819
Balance at end of period	$ 842,819