Stock-Based Compensation - Additional Information (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	9 Months Ended
	Jun. 30, 2011	Jun. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation expense related to awards given under annual bonus plan to employees	$ 11.0	$ 24.1
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unearned stock based compensation expense	5.9	5.9
Weighted average remaining recognition period		0.8
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price for restricted units, vested		$ 0.001
Unearned stock based compensation expense	$ 121.5	$ 121.5
Weighted average remaining recognition period		1.5