Selected Quarterly Financial Data (unaudited) (Tables)

12 Months Ended

Dec. 31, 2015

Quarterly Financial Information Disclosure [Abstract]

Quarterly financial data (Unaudited)

	First quarter		Second quarter		Third quarter		Fourth quarter
	(in thousands, except per share data)
2015
Revenues	$	263,776	$	191,998	$	172,667	$	260,895
Gross profit	67,696		60,554		57,552		71,745
Net earnings	34,976		32,969		29,357		36,151
Net earnings per common share-basic and diluted	$	1.64	$	1.54	$	1.39	$	1.82

	First quarter		Second quarter		Third quarter		Fourth quarter
	(in thousands, except per share data)
2014
Revenues	$	182,115	$	237,509	$	162,842	$	150,540
Gross profit	45,894		58,670		46,849		47,927
Net earnings	20,770		32,216		23,824		22,723
Net earnings per common share-basic and diluted	$	0.97	$	1.51	$	1.12	$	1.06