Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash paid during the period for:
Income taxes, net	$ 15,204	$ 16,023
Interest, net	2,714	1,569
Non-cash transaction information:
Employee stock purchase plan	399	528
Equipment acquired under capital leases	465	1,123
Receivable for sale of Global's assets	$ 1,979	$ 0