Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Current Assets
Cash and cash equivalents	$ 58,298	$ 68,457
Short-term investments	105,760	160,481
Accounts receivable, less allowance for doubtful accounts of $130 and $6 at December 31, 2013 and 2012, respectively	85,814	79,675
Other receivables	18,249	16,253
Inventory, net	90,111	101,377
Prepaid expenses	4,325	4,148
Deferred tax assets, net	17,083	13,055
Total Current Assets	379,640	443,446
Property, plant and equipment, net	76,739	80,246
Deferred tax assets, net	9,622	10,261
Goodwill	3,492	3,492
Other assets	11,180	13,482
Long-term investments	309,225	332,729
Total Assets	789,898	883,656
Current Liabilities
Accounts payable	48,282	42,173
Unearned revenue	22,205	35,326
Accrued expenses	12,776	11,735
Accrued wages and benefits	14,040	15,022
Income tax payable, net	5,002	1,211
Total Current Liabilities	102,305	105,467
Non-current unearned revenue	14,643	22,377
Other non-current liabilities	22,144	17,406
Bonds payable	46,200	46,000
Total Liabilities	185,292	191,250
Commitments and contingencies (see Note 13)
Stockholders' Equity
Common stock, par value $0.01 per share; 200,000 shares authorized; 79,652 shares issued and 56,918 shares outstanding at December 31, 2013 and 79,652 shares issued and 62,310 shares outstanding at December 31, 2012	797	797
Additional paid-in capital	233,511	224,517
Accumulated other comprehensive income	10,753	11,268
Retained earnings	884,451	861,465
Less treasury stock at cost: 22,734 and 17,342 shares at December 31, 2013 and 2012, respectively	(524,906)	(405,641)
Total Stockholders' Equity	604,606	692,406
Total Liabilities and Stockholders' Equity	$ 789,898	$ 883,656