CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Preferred Stock, Par or Stated Value Per Share	$ 1	$ 1
Current assets:
Cash and cash equivalents	$ 146,085	$ 116,305
Investments in marketable securities	48,822	46,006
Accounts receivable, net	104,837	129,103
Inventories	145,507	151,577
Prepaid expenses	8,760	7,051
Deferred tax assets, net	11,857	11,857
Other current assets	45,675	35,756
Total current assets	511,543	497,655
Property, plant and equipment, net	461,843	469,943
Goodwill	3,376	3,376
Intangible Assets, Net (Excluding Goodwill)	21,169	22,732
Deferred tax assets - noncurrent, net	48,957	48,957
Other noncurrent assets, net	13,472	12,605
Total assets	1,060,360	1,055,268
Current liabilities:
Accounts payable	57,933	67,812
Accrued payroll	29,697	28,519
Other accrued liabilities	13,247	9,901
Total current liabilities	100,877	106,232
Long-term liabilities:
Long-term income tax liability	1,736	735
Other long-term liabilities	10,837	11,013
Total liabilities	113,450	117,980
Commitments and contingencies (Note 12)
Stockholders' equity:
Preferred Stock, $0.001 par value	0	0
Common stock, $0.001 par value	166	166
Additional paid-in capital	686,151	678,412
Accumulated other comprehensive income	140	140
Retained earnings	260,453	258,570
Total stockholders' equity	946,910	937,288
Total liabilities and stockholders' equity	$ 1,060,360	$ 1,055,268