Stock-based Compensation (Tables)

6 Months Ended

Mar. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Fair Values of Options, Black-Scholes Option-Pricing Model, Weighted-Average Assumptions

The fair values of the options granted during the six months ended March 31, 2018 were estimated on the dates of grants using the Black-Scholes option-pricing model with the following weighted-average assumptions:

Risk-free interest rate		2.10	%
Expected volatility		26.43	%
Expected life (in years)		5.46
Dividend yield	-

Stock Options Outstanding and Activity During the Period

The following table summarizes all stock option activity for the six months ended March 31, 2018 (in thousands, except share, per share, and time period amounts):

	Options Outstanding			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value1
Balance as of September 30, 2017		2,084,228		$	28.84		6.1	$	46,714
Granted		276,370			55.17
Exercised		(217,397	)		24.46
Canceled/Forfeited		(47,842	)		41.82
Expired		(1,991	)		15.28
Balance as of March 31, 2018		2,093,368		$	32.48		6.2	$	43,646
Vested and expected to vest after March 31, 2018		2,071,674		$	32.32		6.1	$	43,510
Exercisable as of March 31, 2018		1,512,437		$	27.48		5.2	$	38,704

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¹ Aggregate intrinsic value as represents the difference between the closing fair value of the underlying common stock and the exercise price of outstanding, in-the-money options on the date of measurement.

Stock Option Grants, Vesting, and Exercises

The following table summarizes additional information on stock options for the periods presented (in thousands, except per share amounts):

	Six Months Ended March 31,
	2018		2017
Weighted-average fair value of stock options granted	$	15.86	$	14.21
Total fair value of stock options vested		3,832		4,977
Total intrinsic value of stock options exercised		7,700		7,906

Restricted Shares and Units Outstanding and Activity During the Period

The following table summarizes all restricted stock unit activity for the six months ended March 31, 2018:

	RSUs Outstanding			Weighted- Average Grant Date Fair Value
Balance at September 30, 2017		770,973		$	38.95
Granted		370,190			57.40
Performance awards1		41,440			39.56
Released		(189,154	)		31.63
Canceled/Forfeited		(35,974	)		47.65
Balance at March 31, 2018		957,475		$	47.23
Vested and expected to vest after March 31, 2018		936,924		$	47.10

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¹ Additional restricted stock units outstanding as a result of the satisfaction of a performance vesting condition prior to the ascribed time-based vesting condition (release date).

Schedule Of Restricted Stock Units Additional Information

The following table summarizes additional information on RSUs for the periods presented (in thousands, except per share amounts):

	Six Months Ended March 31,
	2018		2017
Weighted-average fair value of RSUs granted	$	57.40	$	47.27
Total fair value of RSUs vested		6,523		2,736
Total intrinsic value of RSUs released		10,924		3,074