Income Taxes (Reconciliation of U.S Statutory Rate to Effective Tax Rate) (Details)	12 Months Ended	36 Months Ended
Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2016
Income Taxes
Statutory tax rate	35.00%	35.00%	35.00%	35.00%
State income taxes, net of federal tax benefit	0.40%	1.20%	1.30%
Taxes on international activities	(2.20%)	(3.80%)	(3.70%)
Research credit	(3.60%)	(0.80%)	(0.70%)
Retroactive extension of research credit	(3.20%)	(2.40%)	0.00%
Net excess income tax benefit from stock-based compensation	(2.60%)	0.00%	0.00%
Domestic production activities deduction	(2.10%)	(1.60%)	(1.30%)
Adjustments of prior period tax items	(0.20%)	(2.10%)	(2.90%)
Other items, net	(1.30%)	(0.80%)	(0.70%)
Effective tax rate	20.20%	24.70%	27.00%

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32698-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h)(2))
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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to deduction for qualified production activity.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to statutory income tax expense (benefit) outside of the country of domicile.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to state and local income tax expense (benefit), net of federal tax expense (benefit).

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to revisions in previously reported amounts of income tax provision and all income tax settlements during the period.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate that can be explained by the restroactive extension of research tax credits to prior periods.

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