Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current Assets
Cash and cash equivalents	$ 82,623	$ 86,433
Short-term investments	16,402	16,129
Accounts receivable, less allowance for doubtful accounts of $— at March 31, 2018 and December 31, 2017	80,883	144,150
Other receivables	35,124	26,578
Inventory, net	120,021	122,542
Prepaid expenses and other current assets	9,693	17,282
Total Current Assets	344,746	413,114
Property, plant and equipment, net	83,875	85,079
Deferred tax assets, net	21,427	23,428
Goodwill	3,492	3,492
Other assets	32,635	13,725
Long-term investments	156,472	130,256
Total Assets	642,647	669,094
Current Liabilities
Accounts payable	50,653	60,632
Unearned revenue	13,948	13,070
Accrued expenses	13,826	13,232
Accrued wages and benefits	15,863	15,948
Income tax payable	8,277	3,936
Total Current Liabilities	102,567	106,818
Non-current unearned revenue	4,154	4,556
Other non-current liabilities	34,590	34,209
Bonds payable	25,600	25,600
Total Liabilities	166,911	171,183
Commitments and contingencies (see Note 15)
Stockholders’ Equity
Common stock, par value $0.01 per share; 200,000 shares authorized; 79,652 shares issued and 47,914 shares outstanding at March 31, 2018 and 79,652 shares issued and 48,485 shares outstanding at December 31, 2017	797	797
Additional paid-in capital	262,333	260,515
Accumulated other comprehensive loss	(5,803)	(3,295)
Retained earnings	909,611	922,178
Less treasury stock at cost: 31,738 and 31,167 shares at March 31, 2018 and December 31, 2017, respectively	(691,202)	(682,284)
Total Stockholders’ Equity	475,736	497,911
Total Liabilities and Stockholders’ Equity	$ 642,647	$ 669,094