Stock Plan - Additional Information (Detail) (USD $)	12 Months Ended						12 Months Ended		104 Months Ended	12 Months Ended		12 Months Ended				1 Months Ended	12 Months Ended							1 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009	Sep. 30, 2011 Restricted stock Senior Management Amended and Restated 2000 Equity Incentive Plan	Sep. 30, 2011 Restricted stock Amended and Restated 2000 Equity Incentive Plan	Sep. 30, 2011 Restricted stock Amended and Restated 2000 Equity Incentive Plan Share Vesting Over Three Year Period	Sep. 30, 2011 Stock options Amended and Restated 2000 Equity Incentive Plan	Sep. 30, 2011 Stock options 1998 Employee Equity Incentive Plan	Sep. 30, 2011 1998 Employee Equity Incentive Plan	Sep. 30, 2011 Stock options 1993 Non-Employee Director Stock Option Plan	Sep. 30, 2011 1993 Non-Employee Director Stock Option Plan	Sep. 30, 2011 Restricted stock Awards subject to performance criteria Senior Management	Sep. 30, 2009 Awards subject to performance criteria	Sep. 30, 2009 Awards subject to performance criteria Selling, General and Administrative Expense	Feb. 22, 1996 Maximum 1995 Employee Stock Purchase Plan	Feb. 29, 1996 1995 Employee Stock Purchase Plan	Sep. 30, 2011 1995 Employee Stock Purchase Plan	Sep. 30, 2011 Stock options	Sep. 30, 2011 Restricted stock Year	Sep. 30, 2010 Restricted stock	Sep. 30, 2009 Restricted stock	Sep. 30, 2011 Restricted stock Senior Management	Sep. 30, 2011 Restricted stock Maximum	Oct. 31, 2005 Acquisition of Helix	Sep. 30, 2011 Acquisition of Helix
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock or units vesting description					These restricted stock awards generally have the following vesting schedules: immediate; three year vesting in which one-half vest at the end of Year 2 and one-half vest at the end of Year 3; and three year vesting in which one-third vest at the end of Year 1, one-third vest at the end of Year 2 and one-third vest at the end of Year 3.
Options forfeited due to employee terminations									3,204,320
Equity incentive plan, vesting period					3 years		4 years	4 years		5 years								4 years					4 years
Equity incentive plan vesting in year one, percentage					33.33%
Equity incentive plan, expiration date							7 years	7 years		10 years
Equity incentive plan vesting in year two, percentage					33.33%	50.00%
Shares of common stock reserved for issuance							9,000,000
Equity incentive plan vesting in year three, percentage					33.33%	50.00%
Options outstanding	370,137	764,621					283,375		8,500		10,000													689,622	68,262
Options to purchase Helix common stock																								765,480
Shares available for grant	5,266,210						4,816,527																		449,683
Restricted stock or units issued net of cancellations					754,874
Awards granted				175,500								183,000	178,346						1,046,000			366,000
Closing stock price	$ 8.15
Total intrinsic value of options exercised	$ 15,000	$ 3,000	$ 0
Cash received from employee stock option exercises	6,000	19,000	0
Compensation expense related to variable compensation award		1,400,000
Compensation expense														1,400,000
Weighted average grant date fair value, Awards granted																			$ 11.27	$ 8.73	$ 4.28
Fair value of restricted stock awards vested																			7,400,000	6,800,000	4,400,000
Unrecognized compensation cost																			$ 10,900,000
Unrecognized compensation cost, estimated weighted average amortization period																			1.8
Employee stock purchase plan, description																Under the 1995 Plan, eligible employees may purchase up to an aggregate of 3,000,000 shares during six-month offering periods commencing on February 1 and August 1 of each year at a price per share of 85% of the lower of the fair market value price per share on the first or last day of each six-month offering period. Participating employees may elect to have up to 10% of their base pay withheld and applied toward the purchase of such shares.
Employee stock purchase plan, offering period																6 months
Employee stock purchase plan, price per share percentage																85.00%
Maximum percentage of base pay withheld and applied toward the purchase of shares																10.00%
Shares of common stock purchased under the 1995 Plan																	2,707,905
Shares of common stock available for purchase															3,000,000		292,095