Stockholders' Equity - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning of period	$ 5,898	$ 15,687	$ 22,604
Other comprehensive (loss) income before reclassifications	8,291	(9,887)	(6,798)
Amounts reclassified from accumulated other comprehensive income	977	98	(119)
Accumulated other comprehensive income (loss), net of tax, end of period	15,166	5,898	15,687
Currency Translation Adjustments
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning of period	6,545	16,102	22,398
Other comprehensive (loss) income before reclassifications	8,844	(9,426)	(6,296)
Amounts reclassified from accumulated other comprehensive income	0	(131)	0
Accumulated other comprehensive income (loss), net of tax, end of period	15,389	6,545	16,102
Unrealized Gains (Losses) on Available-for-Sale Securities
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning of period	103	(38)	66
Other comprehensive (loss) income before reclassifications	(231)	144	(78)
Amounts reclassified from accumulated other comprehensive income	125	(3)	(26)
Accumulated other comprehensive income (loss), net of tax, end of period	(3)	103	(38)
Unrealized Gains (Losses) on Cash Flow Hedges
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning of period	0	0	14
Other comprehensive (loss) income before reclassifications	0	0	79
Amounts reclassified from accumulated other comprehensive income	0	0	(93)
Accumulated other comprehensive income (loss), net of tax, end of period	0	0	0
Pension Liability Adjustments
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning of period	(750)	(377)	126
Other comprehensive (loss) income before reclassifications	(322)	(605)	(503)
Amounts reclassified from accumulated other comprehensive income	852	232	0
Accumulated other comprehensive income (loss), net of tax, end of period	$ (220)	$ (750)	$ (377)

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=36458714&loc=d3e637-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=36458714&loc=d3e681-108580

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14A
-URI http://asc.fasb.org/extlink&oid=36458714&loc=SL7669686-108580

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 31
-Article 5

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

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Amount after tax, before reclassification adjustments of other comprehensive income (loss).

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 55
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=51821188&loc=d3e1436-108581

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Amount after tax of reclassification adjustments of other comprehensive income (loss).

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14A
-URI http://asc.fasb.org/extlink&oid=36458714&loc=SL7669686-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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