CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities
Net income	$ 93,221	$ 192,008	$ 208,712
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	31,857	30,477	31,155
Stock-based compensation expense	12,217	13,125	11,856
Loss (gain) on sale of equipment	(103)	69	(146)
Deferred income taxes	(3,400)	(3,465)	(3,145)
Changes in operating assets and liabilities:
Trade receivables, net	106,544	36,729	(102,696)
Inventories, net	7,873	28,539	(36,814)
Prepaids and other assets	9,816	(17,883)	(13,239)
Excess tax benefits of stock options and awards	(135)	(70)	(558)
Accounts payable and accrued expenses	(11,368)	(89,374)	54,188
Net cash provided by operating activities	246,522	190,155	149,313
Investing activities
Purchase of property, plant and equipment	(25,763)	(27,079)	(42,549)
Proceeds from sale of equipment	357	424	978
Acquisition of business, net of cash acquired	(132,443)	0	0
Net cash used in investing activities	(157,849)	(26,655)	(41,571)
Financing activities
Repurchase of common stock	(24,234)	(75,805)	(190,234)
Proceeds from exercise of stock options	2,206	2,170	2,849
Excess tax benefits of stock options and awards	135	70	558
Net cash used in financing activities	(21,893)	(73,565)	(186,827)
Effect of exchange rate changes on cash activities	(24,619)	(7,304)	(6,566)
Increase (decrease) in cash and cash equivalents	42,161	82,631	(85,651)
Cash and cash equivalents at beginning of year	381,336	298,705	384,356
Cash and cash equivalents at end of year	$ 423,497	$ 381,336	$ 298,705