Quarterly Financial Information (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Quarterly information

The following tables present selected quarterly information (in thousands, except per share data):

	2017
	Quarters Ended
	March 31		June 30		September 30		December 31
Revenues	$	949,525	$	1,066,421	$	1,152,261	$	1,200,221
Gross profit	480,564		544,218		569,901		580,596
Net income	42,062		45,805		79,900		65,215
EPS
Basic EPS	0.58		0.59		1.02		0.83
Diluted EPS	0.57		0.58		1.02		0.82

	2016
	Quarters Ended
	March 31			June 30		September 30		December 31
Revenues	$	844,156		$	900,510	$	924,676	$	942,647
Gross profit	416,476			443,543		454,374		476,726
Net income (loss)	(31,111		)	44,711		51,450		61,750
EPS
Basic EPS	(0.46		)	0.64		0.73		0.86
Diluted EPS	(0.46		)	0.64		0.72		0.86