Postretirement Benefits - Additional Information (Detail) (USD $)	12 Months Ended			3 Months Ended	12 Months Ended			1 Months Ended			12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2012 Helix Plan	Sep. 30, 2012 Helix Plan	Sep. 30, 2012 Nexus Plan	Sep. 30, 2011 Nexus Plan	Jul. 25, 2011 Nexus Plan Risk benefits (disability and death) Y	Jul. 25, 2011 Nexus Plan Pension plans Y	Sep. 30, 2012 Taiwan Plan Assets	Sep. 30, 2012 Worldwide Defined Contribution Plans	Sep. 30, 2011 Worldwide Defined Contribution Plans	Sep. 30, 2010 Worldwide Defined Contribution Plans	Sep. 30, 2012 Market Related Valuation of Assets	Sep. 30, 2012 Other actuarial losses
Defined Benefit Plan Disclosure [Line Items]
Settlements paid	$ 18,928,000			$ 6,400,000
Pension settlement	8,937,000			8,900,000
Minimum age for employees to be admitted into plan								17	24
Accumulated other comprehensive income, unrecognized net actuarial losses	1,100,000	8,900,000												44,000	1,026,000
Net actuarial loss in accumulated other comprehensive income that is expected to be recognized as a component of net periodic pension cost	6,000
Investment gains or losses recognition period, years														5 years
Discount rate	1.89%	3.76%	4.75%			1.90%	2.30%
Expected return on assets	2.18%	4.68%	8.00%
Fair value of plan assets	8,015,000	20,173,000	9,990,000			7,500,000				500,000
Voluntary contribution				6,400,000
Required minimum contributions	1,200,000				700,000
Expected contribution to the Plan to meet minimum funding targets	500,000
Employer contributions	$ 7,684,000	$ 778,000									$ 3,100,000	$ 2,900,000	$ 2,600,000