Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Condensed Financial Statements, Captions [Line Items]
Restructuring expenses	$ (13)	$ (110)	$ (101)	$ (308)
Revenue	434,124	402,729	840,938	782,201
Gross profit	206,732	183,322	398,053	361,012
Net earnings	$ 51,413	$ 45,368	$ 93,984	$ 46,493
Basic earnings per share:
Basic earnings per share (in dollars per share)	$ 0.38	$ 0.33	$ 0.69	$ 0.34
Diluted earnings per share:
Diluted earnings per share (in dollars per share)	$ 0.37	$ 0.33	$ 0.68	$ 0.33