Acquisitions (Unaudited Supplemental Pro Forma Results Of Operations) (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Business Acquisition [Line Items]
Revenues	$ 1,685,201	$ 1,291,979	$ 4,640,635	$ 3,261,170
Gross profit	280,434	204,946	713,312	462,488
Selling, general and administrative expenses	124,276	97,051	346,761	291,534
Amortization of intangible assets	10,504	10,735	29,536	30,984
Net income attributable to common stock	$ 96,398	$ 54,082	$ 208,028	$ 76,581
Earnings per share attributable to common stock:
Basic	$ 0.45	$ 0.25	$ 0.98	$ 0.35
Diluted	$ 0.45	$ 0.25	$ 0.98	$ 0.35