Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Current Assets
Cash and cash equivalents	$ 68,457	$ 42,979
Short-term investments	160,481	159,347
Accounts receivable, less allowance for doubtful accounts of $6 and $8 at December 31, 2012 and 2011, respectively	81,194	76,130
Other receivables	16,253	9,743
Inventory	102,583	87,800
Prepaid expenses	4,148	3,119
Deferred tax assets, net	13,055	12,125
Total Current Assets	446,171	391,243
Property, plant and equipment, net	80,246	75,295
Deferred tax assets, net	10,261	8,345
Goodwill	3,492	3,492
Other assets	13,482	7,131
Long-term investments	332,729	332,008
Total Assets	886,381	817,514
Current Liabilities
Accounts payable	42,173	29,404
Unearned revenue	38,051	9,965
Accrued expenses	10,309	5,876
Accrued wages and benefits	15,022	13,518
Income tax payable, net	1,211	3,169
Total Current Liabilities	106,766	61,932
Non-current unearned revenue	23,803	4,874
Other non-current liabilities	17,406	12,077
Bonds payable	46,000	46,500
Total Liabilities	193,975	125,383
Commitments and contingencies (see Note 12)
Stockholders' Equity
Common stock, par value $0.01 per share; 200,000 shares authorized; 79,652 shares issued and 62,310 shares outstanding at December 31, 2012 and 79,652 shares issued and 63,703 shares outstanding at December 31, 2011	797	797
Additional paid-in capital	224,517	213,560
Accumulated other comprehensive income	11,268	13,102
Retained earnings	861,465	840,206
Less treasury stock at cost: 17,342 and 15,949 shares at December 31, 2012 and 2011, respectively	(405,641)	(375,534)
Total Stockholders' Equity	692,406	692,131
Total Liabilities and Stockholders' Equity	$ 886,381	$ 817,514