Acquisitions - Unaudited Supplemental ProForma Results of Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Business Combinations [Abstract]
Revenues	$ 1,792,430	$ 1,916,000	$ 3,513,472	$ 3,835,457
Gross profit	200,217	235,282	403,682	484,237
Selling, general and administrative expenses	156,607	154,023	315,817	305,998
Amortization of intangible assets	8,141	9,910	15,792	19,648
Net income from continuing operations	16,729	37,053	37,069	91,347
Net income from continuing operations attributable to common stock	$ 16,562	$ 33,597	$ 36,539	$ 83,190
Earnings per share from continuing operations attributable to common stock - basic and diluted	$ 0.11	$ 0.16	$ 0.23	$ 0.39