Condensed Consolidated Balance Sheets (USD $)	Mar. 31, 2013	Dec. 31, 2012		Sep. 30, 2012	Dec. 31, 2011
CURRENT ASSETS:
Cash and cash equivalents	$ 154,631,000	$ 146,900,000		$ 154,631,000
Investment securities	78,929,000	79,259,000	[1]
Cash, cash equivalents and investment securities	233,560,000	226,159,000	[1]
Accounts receivable, net of allowance for doubtful accounts of $824 at March 31, 2013 and $998 at December 31, 2012	52,943,000	49,127,000	[1]
Inventories	36,540,000	36,333,000	[1]
Prepaid income taxes	289,000	2,320,000	[1]
Prepaid expenses and other current assets	6,007,000	7,271,000	[1]
Deferred income taxes	4,788,000	4,293,000	[1]
Total current assets	334,127,000	325,503,000	[1]
PROPERTY AND EQUIPMENT, net	86,994,000	85,937,000	[1]
GOODWILL	1,478,000	1,478,000	[1]
INTANGIBLE ASSETS, net	9,647,000	9,952,000	[1]
DEFERRED INCOME TAXES	5,636,000	5,642,000	[1]
TOTAL ASSETS	437,882,000	428,512,000	[1]
CURRENT LIABILITIES:
Accounts payable	11,040,000	11,308,000	[1]
Accrued liabilities	14,527,000	17,810,000	[1]
Total current liabilities	25,567,000	29,118,000	[1]
DEFERRED INCOME TAXES	5,539,000	5,247,000	[1]
INCOME TAX LIABILITY	3,290,000	3,290,000	[1]
COMMITMENTS AND CONTINGENCIES
STOCKHOLDERS' EQUITY:
Convertible preferred stock, $1.00 par value Authorized-500 shares; Issued and outstanding - none	0	0	[1]
Common stock, $0.10 par value - Authorized-80,000 shares; Issued 14,855 shares at March 31, 2013 and December 31, 2012, outstanding 14,579 shares at March 31, 2013 and 14,458 shares at December 31, 2012	1,486,000	1,486,000	[1]
Additional paid-in capital	65,736,000	63,770,000	[1]
Treasury stock, at cost - 276 shares at March 31, 2013 and 397 shares at December 31, 2012	(10,780,000)	(15,128,000)	[1]
Retained earnings	350,843,000	342,158,000	[1]
Accumulated other comprehensive loss	(3,799,000)	(1,429,000)	[1]
Total stockholders' equity	403,486,000	390,857,000	[1]
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	437,882,000	428,512,000	[1]
Allowance for doubtful accounts				824,000	998,000
Convertible preferred stock, par value				$ 1.00	$ 1.00
Convertible preferred stock, authorized shares				500,000	500,000
Convertible preferred stock, issued shares				$ 0	$ 0
Convertible preferred stock, outstanding shares				0	0
Common stock, par value				$ 0.10	$ 0.10
Common stock, shares authorized				80,000,000	80,000,000
Common stock, shares issued				14,855,000	14,855,000
Common stock, shares outstanding				14,579,000	14,458,000
Treasury Stock, shares				276,000	397,000

[1] December 31, 2012 balances were derived from audited consolidated financial statements.