CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Cash flows from operating activities:
Net income	$ 10,374	$ 15,902
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	13,504	12,572
Amortization of deferred loan costs	229	229
Stock-based compensation	877	817
Excess tax benefit from stock-based compensation	(395)
Provision (recoveries) of bad debts	79	(74)
Loss on disposal of assets	249
Changes in operating assets and liabilities:
Receivables	(969)	299
Inventories	59	(77)
Prepaid expenses	(666)	(263)
Accounts payable	(795)	4
Accrued expenses	(172)	(347)
Income taxes	408	(693)
Net cash provided by operating activities	22,782	28,369
Cash flows from investing activities:
Proceeds from sale of assets	84
Change in construction payable	766
Acquisition of property and equipment	(13,019)	(8,220)
Net cash used in investing activities	(12,169)	(8,220)
Cash flows from financing activities:
Net exercise of stock options	(2,428)	3,119
Excess tax benefit from stock-based compensation	395
Principal payments on long-term debt	(10,400)	(24,800)
Net cash used in financing activities	(12,433)	(21,681)
Net decrease in cash	(1,820)	(1,532)
Cash and cash equivalents at beginning of period	19,330	19,043
Cash and cash equivalents at end of period	17,510	17,511
Supplemental disclosure of cash flow information:
Cash paid for interest,net of amounts capitalized	607	1,234
Cash paid for income taxes	$ 5,550	$ 9,590