Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 8,799	$ 15,502
Restricted cash (Note 8)	4,512	4,592
Certificates of deposit	245	488
Marketable securities		1,842
Accounts receivable	25,580	18,428
Prepaid income taxes	1,562	2,606
Inventory	28,297	20,507
Parts and supplies, net of allowance of $274 and $1,595, respectively	11,775	9,645
Prepaid expenses	1,678	11,368
Total current assets	82,448	84,978
Property, plant and equipment, at cost:
Land and mineral rights	114,722	130,897
Building and equipment	351,614	365,481
Mine development	84,160	140,990
Total property, plant and equipment, at cost	550,496	637,368
Less - accumulated DD&A	(220,780)	(224,730)
Total property, plant and equipment, net	329,716	412,638
Investment in subsidiaries (Note 16)	3,139	3,666
Other assets (Note 4)	10,324	14,217
Total assets	425,627	515,499
Current liabilities:
Current portion of bank debt, net (Note 5)	33,044	25,392
Accounts payable and accrued liabilities (Note 6)	31,800	26,421
Total current liabilities	64,844	51,813
Long-term liabilities:
Bank debt, net (Note 5)	140,594	155,655
Deferred income taxes (Note 9)	4,619	26,441
Asset retirement obligations (ARO)	15,694	14,586
Other	4,346	8,130
Total long-term liabilities	165,253	204,812
Total liabilities	230,097	256,625
Redeemable noncontrolling interests (Note 17)	4,000	4,000
Stockholders' equity:
Preferred stock, $.10 par value, 10,000 shares authorized; none issued
Common stock, $.01 par value, 100,000 shares authorized; 30,420 and 30,245 issued and outstanding, respectively	304	302
Additional paid-in capital	102,215	100,742
Retained earnings	89,011	153,830
Total stockholders' equity	191,530	254,874
Total liabilities , redeemable noncontrolling interests, and stockholders' equity	$ 425,627	$ 515,499