CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Operating activities
Net income	$ 93,942	$ 82,769
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	15,126	14,353
Stock-based compensation expense	5,660	4,136
Gain on sale of equipment	(149)	(22)
Deferred income taxes	(2,507)	(1,751)
Changes in operating assets and liabilities:
Trade receivables, net	(33,272)	15,203
Inventories, net	(32,708)	(24,658)
Prepaids and other assets	(3,460)	(921)
Excess tax benefits of stock option and awards	(251)	(1,682)
Accounts payable and accrued expenses	24,291	(1,326)
Net cash provided by operating activities	66,672	86,101
Investing activities
Purchase of property, plant and equipment	(23,218)	(23,101)
Proceeds from sale of equipment	470	299
Net cash used in investing activities	(22,748)	(22,802)
Financing activities
Repurchase of common stock	(90,022)
Proceeds from exercise of stock options	1,386	7,749
Excess tax benefits of stock options and awards	251	1,682
Net cash provided by (used in) financing activities	(88,385)	9,431
Effect of exchange rate changes on cash activities	2,726	(4,380)
Increase (decrease) in cash and cash equivalents	(41,735)	68,350
Cash and cash equivalents at beginning of period	384,356	257,191
Cash and cash equivalents at end of period	$ 342,621	$ 325,541