Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Operating activities
Net income	$ 33,883	$ 62,208
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	23,394	21,801
Provision for doubtful accounts	28	12
Deferred income taxes	2,609	5,299
Excess tax benefits from stock based compensation	(67)	(1,257)
Gain on disposal or impairment of assets	(40)	(54)
Foreign currency transaction loss (gain), net	31	(144)
Stock compensation expense	3,189	3,087
Changes in operating assets and liabilities:
Trade accounts and other receivables	(6,540)	(5,525)
Inventories	(2,372)	1,938
Prepaid expenses and other current assets	(3,466)	(1,451)
Long-term prepaid expenses	1,711	766
Accounts payable	(4,845)	(18,142)
Accrued expenses	(6,748)	(12,482)
Accrued income taxes, net	(4,054)	5,764
Net cash provided by operating activities	36,713	61,820
Investing activities
Capital expenditures	(31,169)	(50,288)
Net cash used in investing activities	(31,169)	(50,288)
Financing activities
Proceeds from bank borrowings		10,000
Repayments on bank borrowings		(10,000)
Dividends paid	(12,503)	(11,095)
Purchase of common stock	(6,821)	(7,655)
Excess tax benefits from stock based compensation	67	1,257
Net cash used in financing activities	(19,257)	(17,493)
Effect of exchange rate changes on cash	(899)	(443)
Net (decrease) increase in cash and cash equivalents	(14,612)	(6,404)
Cash and cash equivalents at beginning of period	90,635	41,270
Cash and cash equivalents at end of period	76,023	34,866
Supplemental cash flow information
Interest paid	3	72
Income taxes paid	$ 17,153	$ 20,621