Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Condensed Financial Statements, Captions [Line Items]
Restructuring expenses	$ 542	$ 910	$ 642	$ 1,217
Revenue	464,712	405,228	1,305,650	1,187,429
Gross profit	222,891	191,376	620,944	552,388
Net earnings	$ 63,529	$ 58,633	$ 157,513	$ 105,126
Basic earnings per share:
Basic earnings per share (in dollars per share)	$ 0.46	$ 0.43	$ 1.15	$ 0.76
Diluted earnings per share:
Diluted earnings per share (in dollars per share)	$ 0.46	$ 0.43	$ 1.13	$ 0.76