CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities:
Net income	$ 9,142	$ 6,300
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	8,239	9,324
Amortization of deferred loan costs	152	152
Stock-based compensation	620	576
Excess tax benefit from stock-based compensation	(275)	(395)
Provision for bad debts	35	34
Loss (gain) on disposition of assets	(20)	249
Changes in operating assets and liabilities:
Receivables	(83)	(745)
Inventories	258	249
Prepaid expenses	(43)	(458)
Accounts payable	(1,499)	(744)
Accrued expenses	(830)	(1,206)
Income taxes	(798)	770
Net cash provided by operating activities	14,898	14,106
Cash flows from investing activities:
Proceeds from sale of assets	23	75
Change in construction payable	442	119
Acquisition of property and equipment	(15,202)	(9,498)
Net cash used in investing activities	(14,737)	(9,304)
Cash flows from financing activities:
Net exercise of stock options	1,929	(2,461)
Excess tax benefit from stock-based compensation	275	395
Principal payments on long-term debt	(4,100)	(4,900)
Net cash used in financing activities	(1,896)	(6,966)
Net decrease in cash	(1,735)	(2,164)
Cash and cash equivalents at beginning of period	21,583	19,330
Cash and cash equivalents at end of period	19,848	17,166
Supplemental disclosure of cash flow information:
Cash paid for interest, net of amounts capitalized	247	447
Cash paid for income taxes	$ 5,500	$ 2,850