CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 47,774	$ 58,332
Trade receivables, net	16,727	17,444
Inventories	13,637	13,436
Prepaid expenses and other current assets	1,353	2,550
Total current assets	79,491	91,762
Property, plant and equipment	266,815	262,462
Less accumulated depreciation and depletion	(160,209)	(153,949)
Property, plant and equipment, net	106,606	108,513
Other assets, net	140	145
Total assets	186,237	200,420
Current liabilities:
Current installments of debt		16,667
Accounts payable	3,587	5,166
Accrued expenses	2,196	3,132
Total current liabilities	5,783	24,965
Deferred tax liabilities, net	19,616	19,259
Other liabilities	1,181	1,505
Total liabilities	26,580	45,729
Stockholders' equity:
Common stock	653	652
Additional paid-in capital	20,993	20,418
Accumulated other comprehensive loss		(1,024)
Retained earnings	188,234	184,710
Less treasury stock, at cost	(50,223)	(50,065)
Total stockholders' equity	159,657	154,691
Total liabilities and stockholders' equity	$ 186,237	$ 200,420

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

Name:	us-gaap_AccountsPayableCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.