Share-Based Compensation (Tables)

12 Months Ended

Sep. 30, 2015

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

Fair value is estimated at the grant date based on a Black-Scholes-Merton option-pricing model using the following weighted-average assumptions:

	Year Ended September 30,
	2015		2014		2013
Expected stock price volatility	28	%	34	%	35	%
Expected dividend yield	—	%	—	%	—	%
Risk free interest rate	0.66	%	0.80	%	0.37	%
Average expected life (in years)	3.22		2.88		2.88

Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]

The following is a summary of stock option activity for the year ended September 30, 2015:

	Shares Available for Grant		Number of Options Outstanding		Weighted Average  Exercise Price		Weighted Average Grant Date Fair Value		Weighted Average Remaining Term (in years)	Aggregate Intrinsic Value ($ millions)
Balances at September 30, 2014	913,500		1,578,056		$	25.38	$	11.58	4.16	$	1.9
Granted	(91,000	)	91,000		$	20.54	$	4.31
Exercised			(316,048	)	$	11.87	$	6.42
Forfeited	—		(9,665	)	$	19.35	$	4.83
Expired	—		(45,359	)	$	27.92	$	12.08
Balances at September 30, 2015	822,500		1,297,984		$	28.28	$	12.37	4.24	$	1.8
Exercisable at September 30, 2015			355,350		$	37.93	$	13.55	1.29	$	0.9

Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block]

The options outstanding as of September 30, 2015 broken down by exercise price are as follows:

Exercise Price					Number of Options Outstanding	Weighted Average Exercise Price		Weighted Average Remaining Term (in Years)
$	—	-	$	5.00	—	n/a		n/a
$	5.00	-	$	10.00	—	n/a		n/a
$	10.00	-	$	15.00	—	n/a		n/a
$	15.00	-	$	20.00	220,525	$	18.57	1.32
$	20.00	-	$	25.00	168,000	$	21.97	2.77
$	25.00	-	$	30.00	720,000	$	25.91	6.22
$	30.00	-	$	35.00	—	n/a		n/a
$	35.00	-	$	40.00	—	n/a		n/a
$	40.00	-	$	45.00	—	n/a		n/a
$	45.00	-	$	50.00	—	n/a		n/a
$	50.00	-	$	55.00	189,459	$	54.23	1.41
					1,297,984	$	28.28	4.24

Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block]

The following is a summary of restricted stock activity through September 30, 2015:

	Shares Available for Grant		Number of Shares Outstanding		Weighted Average Grant Date Fair Value		Weighted Average Remaining Term (in years)	Aggregate Intrinsic Value ($ millions)
Balances at September 30, 2014	1,096,325		229,851		$	20.03	1.79	$	4.0
Granted	(126,148	)	126,148		$	21.16
Vested			(121,214	)	$	21.16
Forfeited	4,742		(4,742	)	$	18.24
Balances at September 30, 2015	974,919		230,043		$	20.10	2.17	$	5.7