Acquisitions - Unaudited Supplemental Pro Forma Results of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Business Combinations [Abstract]
Revenues	$ 2,811,139	$ 2,454,974
Gross profit	364,779	313,628
Selling, general and administrative expenses	232,361	220,234
Amortization of intangible assets	12,868	12,982
Net income	121,021	41,715
Net income attributable to common stock	$ 120,474	$ 40,718
Earnings per share:
Basic (in dollars per share)	$ 0.83	$ 0.26
Diluted (in dollars per share)	$ 0.82	$ 0.26