CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating activities
Net income	$ 91,919	$ 143,654
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	23,092	22,777
Stock-based compensation expense	9,442	9,794
(Gain) loss on sale of equipment	(93)	73
Deferred income taxes	(3,435)	(7,420)
Changes in operating assets and liabilities:
Trade receivables, net	92,075	60,329
Inventories, net	(12,515)	8,993
Prepaids and other assets	34,350	(8,747)
Excess tax benefits of stock options and awards	(58)	(57)
Accounts payable and accrued expenses	(13,283)	(70,658)
Net cash provided by operating activities	221,494	158,738
Investing activities
Purchase of property, plant and equipment	(20,289)	(16,746)
Proceeds from sale of equipment	281	183
Net cash used in investing activities	(20,008)	(16,563)
Financing activities
Repurchase of common stock	(24,238)	(40,911)
Proceeds from exercise of stock options	940	1,952
Excess tax benefits of stock options and awards	58	57
Net cash used in financing activities	(23,240)	(38,902)
Effect of exchange rate changes on cash activities	(16,952)	(5,009)
Increase in cash and cash equivalents	161,294	98,264
Cash and cash equivalents at beginning of period	381,336	298,705
Cash and cash equivalents at end of period	$ 542,630	$ 396,969