Condensed Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
CURRENT ASSETS:
Cash and cash equivalents	$ 257,894	$ 296,871
Accounts receivable, net of allowance for doubtful accounts	68,507	56,754
Inventories, net	71,865	63,238
Prepaid expenses	5,757	7,615
Other current assets	2,935	2,841
Total Current Assets	406,958	427,319
Property, plant and equipment, net	1,005,759	979,164
Deposits on equipment	1,295	1,895
Operating leases	3,237	3,616
Long term investment in equity securities	33,446	23,528
Other assets	29,895	28,899
Total Assets	1,480,590	1,464,421
CURRENT LIABILITIES:
Accounts payable	46,591	36,096
Accrued expenses	32,193	49,816
Operating lease liabilities	1,174	1,312
Finance lease liabilities	1,988	1,998
Total Current Liabilities	81,946	89,222
Convertible senior notes	393,588	393,074
Long term operating lease liabilities	2,333	2,591
Long term finance lease liabilities	24,879	26,080
Total Liabilities	502,746	510,967
Commitments and contingencies
STOCKHOLDERS' EQUITY:
Common stock — voting, $0.001 par value, 200,000 shares authorized, 48,449 issued and 48,435 outstanding on March 31, 2024, and 48,277 issued and 48,263 outstanding on December 31, 2023	48	48
Additional paid-in capital	1,288,890	1,282,984
Accumulated deficit	(310,129)	(328,731)
Accumulated other comprehensive loss	(709)	(591)
Treasury stock, at cost — 14 shares on March 31, 2024 and on December 31, 2023	(256)	(256)
Total Stockholders' Equity	977,844	953,454
Total Liabilities and Stockholders' Equity	$ 1,480,590	$ 1,464,421