Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 5,470	$ 121,701
Accounts receivable, net	263,863	106,748
Inventories	77,232	68,238
Prepaid expenses and other assets	30,386	25,310
Total current assets	376,951	321,997
Property, plant and equipment, net	404,990	336,537
Goodwill and other intangible assets, net	73,456	73,665
Operating lease assets	37,924	34,382
Other assets	5,499	3,911
Total assets	898,820	770,492
Current liabilities:
Accounts payable	42,876	38,622
Accrued expenses and other liabilities	73,780	62,331
Accrued warranty	5,400	5,400
Line of credit	49,500
Total current liabilities	171,556	106,353
Operating lease liabilities	31,441	28,579
Non-current accrued warranty	24,091	24,073
Deferred income taxes	22,956	22,956
Total liabilities	250,044	181,961
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.01 par value, 3,000,000 shares authorized; none issued and outstanding
Common stock, $0.01 par value, 180,000,000 shares authorized; 140,667,233 and 140,577,005 shares issued and 115,344,705 and 115,799,503 shares outstanding at June 30, 2021 and December 31, 2020, respectively	1,407	1,406
Additional paid-in capital	125,764	126,087
Retained earnings	847,221	737,311
Treasury stock, at cost, 25,322,528 and 24,777,502 shares at June 30, 2021 and December 31, 2020, respectively	(325,616)	(276,273)
Total stockholders' equity	648,776	588,531
Total liabilities and stockholders' equity	$ 898,820	$ 770,492