Income Taxes - Unrecognized Tax Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2017	Sep. 30, 2016
Income Taxes [Abstract]
Unrecognized Tax Benefits Beginning Balance	$ 55,867	$ 55,963
Unrecognized Tax Benefits, Increases Resulting from Current Period Tax Positions	207	0
Unrecognized Tax Benefits, Increases Resulting from Prior Period Tax Positions	0	0
Unrecognized Tax Benefits, Reductions Resulting from Lapse of Applicable Statute of Limitations	3,707	27
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions	399	69
Unrecognized Tax Benefits, Decreases Resulting from Settlements with Taxing Authorities	0	0
Unrecognized Tax Benefits Ending Balance	$ 51,968	$ 55,867

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- Definition

Amount of unrecognized tax benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=65882285&loc=SL6600010-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Unrecognized Tax Benefit
-URI http://asc.fasb.org/extlink&oid=6527854

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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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