Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Income Tax [Line Items]
Net current deferred tax	$ 253,577,000	$ 287,143,000
Net non-current deferred tax assets	137,294,000	111,786,000
Net current deferred tax liabilities	3,882,000	7,522,000
Net non-current deferred tax liabilities	72,330,000	58,553,000
Cumulative amount of undistributed earnings reinvested in foreign operation	4,400,000,000
Accrued unrecognized tax benefits Interest and Penalties	9,821,000
Unrecognized tax benefits interest and penalties reflected in current year	844,000
Tax reductions related to tax holidays	83,240,000	60,275,000	51,300,000
Expiration period of tax holidays	Through 2026
Net of income tax refunds	$ 217,724,000	$ 512,092,000	$ 391,965,000
Maximum [Member]
Income Tax [Line Items]
Expiration period of deferred tax assets	2014
Minimum [Member]
Income Tax [Line Items]
Expiration period of deferred tax assets	2013