Consolidated Statements of Cash Flows (USD $)	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012		Sep. 30, 2011
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ 10,480,000	$ 11,113,000	[1]	$ (3,246,000)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation	37,095,000	32,498,000		30,536,000
Noncash compensation	1,797,000	1,489,000		1,671,000
Deferred income tax expense	8,273,000	4,913,000		3,368,000
Provision for bad debts	63,000	327,000		231,000
Other	(118,000)	192,000		(516,000)
Change in current assets and liabilities:
Decrease (increase) in accounts receivable	16,168,000	32,670,000		(30,613,000)
Decrease in prepaid expenses and other assets	25,000	3,359,000		3,402,000
(Decrease) increase in accounts payable	(2,952,000)	(1,593,000)		3,628,000
Decrease in accrued liabilities	(223,000)	(2,439,000)		(922,000)
(Decrease) increase in deferred revenue	(29,000)	(6,149,000)		9,412,000
Net cash provided by operating activities	70,579,000	76,380,000		16,951,000
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures, net of noncash capital expenditures summarized below in noncash investing and financing activities	(48,485,000)	(44,832,000)		(58,550,000)
Proceeds from maturity of short-term investments	10,750,000	500,000		22,500,000
Acquisition of short-term investments	(30,250,000)	(4,500,000)		(2,500,000)
Proceeds from disposal of assets	481,000	252,000		741,000
Partial proceeds on fire insurance claim				1,392,000
Net cash used by investing activities	(67,504,000)	(48,580,000)		(36,417,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from notes payable	983,000	9,346,000		16,427,000
Principal payments on notes payable	(8,898,000)	(5,814,000)		(856,000)
Principal payments on capital lease obligations	(736,000)	(220,000)
Proceeds from exercise of stock options	608,000	184,000		297,000
Net cash (used) provided by financing activities	(8,043,000)	3,496,000		15,868,000
Net (decrease) increase in cash and cash equivalents	(4,968,000)	31,296,000		(3,598,000)
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	57,373,000	26,077,000		29,675,000
CASH AND CASH EQUIVALENTS AT END OF PERIOD	52,405,000	57,373,000		26,077,000
SUPPLEMENTAL CASH FLOW INFORMATION:
Cash paid for interest	688,000	618,000		115,000
Cash paid for income taxes	1,665,000	262,000		509,000
Cash received for income taxes	42,000	3,258,000		7,366,000
NONCASH INVESTING AND FINANCING ACTIVITIES:
Increase in accrued purchases of property and equipment	288,000	1,405,000		830,000
Capital lease obligations incurred	$ 1,296,000	$ 1,427,000

[1] The 2012 earnings per share calculations have been adjusted for the two-class method to reflect restricted shares that were not reflected as participating in the prior period. Basic earnings per share as previously reported for year ended September 30, 2012 was $1.42. Diluted earnings per share as previously reported for the year-ended September 30, 2012 was $1.40. Basic weighted average shares outstanding as previously reported for the year ended September 30, 2012 was 7,841,722. Diluted weighted average shares outstanding as previously reported for the year ended September 30, 2012 was 7,931,593. The impact on all prior period financial statements is deemed immaterial.