CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating activities
Net income	$ 84,886	$ 105,933	$ 130,136
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	47,472	44,893	36,015
Provision for doubtful accounts	354	19	229
Deferred income taxes	10,121	11,212	4,223
Excess tax benefits from stock based compensation	(134)	(1,384)	(1,399)
(Gain) loss on disposal or impairment of assets	(43)	518	1,548
Foreign currency transaction loss, net	17	76	135
Stock compensation expense	5,837	5,335	4,719
Changes in operating assets and liabilities:
Trade accounts and other receivables	(22,024)	8,945	(23,101)
Inventories	6,068	(7,589)	(41,704)
Prepaid expenses and other current assets	(1,136)	(150)	(1,142)
Long-term prepaid expenses	2,969	12,005	(24,083)
Accounts payable	4,330	(18,201)	15,971
Accrued expenses	1,677	(10,628)	11,846
Accrued income taxes, net	(2,823)	5,397	(1,980)
Net cash provided by operating activities	137,571	156,381	111,413
Investing activities
Capital expenditures	(99,936)	(77,189)	(90,395)
Net cash used in investing activities	(99,936)	(77,189)	(90,395)
Financing activities
Proceeds from bank borrowings		10,000
Repayments on bank borrowings		(10,000)
Net proceeds from stock based compensation		54	76
Dividends paid	(26,350)	(23,563)	(20,369)
Purchase of common stock	(6,958)	(7,927)	(7,550)
Excess tax benefits from stock based compensation	134	1,384	1,399
Net cash used in financing activities	(33,174)	(30,052)	(26,444)
Effect of exchange rate changes on cash	(846)	225	40
Net increase (decrease) in cash and cash equivalents	3,615	49,365	(5,386)
Cash and cash equivalents at beginning of year	90,635	41,270	46,656
Cash and cash equivalents at end of year	94,250	90,635	41,270
Supplemental cash flow information
Interest paid	10	78	1
Income taxes paid	$ 33,015	$ 36,036	$ 65,071