Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 14,449	$ 12,483
Restricted cash (Note 8)	4,115	3,811
Certificates of deposit	1,495	1,495
Marketable securities	1,795	1,907
Accounts receivable	14,827	16,762
Prepaid income taxes	2,521	2,899
Coal inventory	20,949	12,804
Parts and supply inventory	11,134	10,043
Prepaid expenses	12,210	9,433
Total current assets	83,495	71,637
Property, plan and equipment, at cost:
Land and mineral rights	130,660	129,724
Buildings and equipment	362,636	356,911
Mine development	137,682	136,762
Total property, plan and equipment, at cost	630,978	623,397
Less - accumulated DD&A	(214,189)	(203,391)
Total property, plant and equipment, net	416,789	420,006
Investment in subsidiaries (Note 4)	3,770	11,890
Other assets (Note 5)	14,778	14,660
Total assets	518,832	518,193
Current liabilities:
Current portion of bank debt, net (Note 3)	33,171	33,171
Accounts payable and accrued liabilities (Note 6)	24,903	21,115
Total current liabilities	58,074	54,286
Long-term liabilities:
Bank debt, net (Note 3)	154,975	165,773
Deferred income taxes	29,097	28,728
Asset retirement obligations (ARO)	13,788	13,506
Other	6,711	6,577
Total long-term liabilities	204,571	214,584
Total liabilities	262,645	268,870
Redeemable noncontrolling interests (Note 13)	4,000
Stockholders' equity:
Preferred stock, $.10 par value, 10,000 shares authorized; none issued
Common stock, $.01 par value, 100,000 shares authorized; 29,956 and 29,955 shares outstanding, respectively	299	299
Additional paid-in capital	99,841	97,873
Retained earnings	152,047	150,236
Accumulated other comprehensive income		915
Total stockholders' equity	252,187	249,323
Total liabilities, redeemable noncontrolling interests, and stockholders' equity	$ 518,832	$ 518,193