Share-Based Compensation (Tables)

12 Months Ended

Sep. 30, 2016

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,
	2016		2015		2014
Expected stock price volatility	28	%	28	%	34	%
Expected dividend yield	—	%	—	%	—	%
Risk free interest rate	0.83	%	0.66	%	0.80	%
Average expected life (in years)	3.06		3.22		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, 2016:

	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, 2015	828,665		1,297,984		$	28.28	$	12.37	4.24	$	1.8
Granted	(90,500	)	90,500		$	31.37	$	6.40
Exercised			(147,205	)	$	18.52	$	1.50
Forfeited	15,998		(16,498	)	$	25.23	$	5.28
Expired			(8,960	)	$	54.23	$	20.04
Balances at September 30, 2016	754,163		1,215,821		$	29.55	$	12.88	3.80	$	14.1
Exercisable at September 30, 2016			306,520		$	40.58	$	15.09	0.92	$	2.2

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, 2016 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	75,325	$	18.77	1.00
$	20.00	-	$	25.00	156,997	$	22.07	1.73
$	25.00	-	$	30.00	720,000	$	25.91	5.38
$	30.00	-	$	35.00	83,000	$	31.37	3.28
$	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	180,499	$	54.23	0.68
					1,215,821	$	29.55	3.80

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, 2016:

	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, 2015	974,919		230,043		$	20.10	2.17	$	5.7
Granted	(229,886	)	229,886		$	31.40
Vested			(99,428	)	$	19.84
Forfeited	2,749		(2,749	)	$	21.89
Balances at September 30, 2016	747,782		357,752		$	27.39	1.39	$	13.9