Stock-Based Compensation - Equity Incentive Plan Activity (Detail) (USD $)	12 Months Ended
	Sep. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Options, Total Options, Outstanding at September 30, 2012	1,579,000
Stock Options, Total Options, Granted	301,000
Stock Options, Total Options, Performance-based adjustment		[1]
Stock Options, Total Options, Exercised / Vested	(245,000)	[2]
Stock Options, Total Options, Cancelled / Forfeited	(12,000)
Stock Options, Total Options, Outstanding at September 30, 2013	1,623,000
Stock Options, Total Options, Exercisable at September 30, 2013	1,029,000
Exercisable and expected to vest	1,611,000	[3]
Stock Options, Weighted Average Exercise Price, Outstanding at September 30, 2012	$ 24.17
Stock Options, Weighted Average Exercise Price, Granted	$ 35.25
Stock Options, Weighted Average Exercise Price, Performance-based adjustment		[1]
Stock Options, Weighted Average Exercise Price, Exercised / Vested	$ 19.10	[2]
Stock Options, Weighted Average Exercise Price, Cancelled / Forfeited	$ 32.04
Stock Options, Weighted Average Exercise Price, Outstanding at September 30, 2013	$ 26.93
Exercisable at September 30, 2013	$ 22.63
Exercisable and expected to vest	$ 26.87	[3]
Stock Options, Weighted Average Grant Date Fair Value, Outstanding at September 30, 2012	$ 7.37
Stock Options, Weighted Average Grant Date Fair Value, Granted	$ 12.46
Stock Options, Weighted Average Grant Date Fair Value, Performance-based adjustment		[1]
Stock Options, Weighted Average Grant Date Fair Value, Exercised / Vested	$ 4.77	[2]
Stock Options, Weighted Average Grant Date Fair Value, Cancelled / Forfeited	$ 7.30
Stock Options, Weighted Average Grant Date Fair Value, Outstanding at September 30, 2013	$ 8.71
Restricted Stock / Units, Outstanding at September 30, 2013	42,304
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock / Units, Outstanding at September 30, 2012	2,000
Restricted Stock / Units, Exercised / Vested	(1,000)	[2]
Restricted Stock / Units, Outstanding at September 30, 2013	1,000
Restricted Stock / Units, Weighted Average Grant Date Fair Value, Outstanding at September 30, 2012	$ 9.56
Restricted Stock / Units, Weighted Average Grant Date Fair Value, Exercised / Vested	$ 9.56	[2]
Restricted Stock / Units, Weighted Average Grant Date Fair Value, Outstanding at September 30, 2013	$ 9.56
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock / Units, Outstanding at September 30, 2012	1,231,000	[4]
Restricted Stock / Units, Granted	417,000	[4]
Restricted Stock / Units, Performance-based adjustment	(142,000)	[1],[4]
Restricted Stock / Units, Exercised / Vested	(440,000)	[2],[4]
Restricted Stock / Units, Cancelled / Forfeited	(27,000)	[4]
Restricted Stock / Units, Outstanding at September 30, 2013	1,039,000	[4]
Restricted Stock / Units, Weighted Average Grant Date Fair Value, Outstanding at September 30, 2012	$ 30.28
Restricted Stock / Units, Weighted Average Grant Date Fair Value, Granted	$ 35.28
Restricted Stock / Units, Weighted Average Grant Date Fair Value, Performance-based adjustment	34.43	[1]
Restricted Stock / Units, Weighted Average Grant Date Fair Value, Exercised / Vested	$ 23.84	[2]
Restricted Stock / Units, Weighted Average Grant Date Fair Value, Cancelled / Forfeited	$ 32.43
Restricted Stock / Units, Weighted Average Grant Date Fair Value, Outstanding at September 30, 2013	$ 34.39

[1] Represents the incremental number of shares cancelled upon vesting of outstanding performance-based restricted stock units, based on the Company achieving performance at a level less than target under the 2013 performance targets.

[2] "Exercised / Vested" includes 160,740 Restricted Stock Units and 379 shares of restricted stock that vested during the year ended September 30, 2013 but were withheld at the request of the award recipient to cover withholding taxes associated with the vesting. The units were added back to the shares available for future issuance under our 2009 Long-Term Incentive Plan.

[3] Stock options exercisable and expected to vest in the future, net of estimated forfeitures.

[4] The number "Granted" represents the number of shares issuable upon vesting of time-based restricted stock units and performance-based restricted stock units, assuming the Company performs at the target performance level in each year of the three-year performance per