Derivative Instruments and Hedging Activities (Narrative) (Details) € in Thousands, ¥ in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2017 CNY (¥)	Mar. 31, 2017 EUR (€)	Mar. 31, 2017 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 CNY (¥)
Net unrecognized gains on terminated derivative instruments expected to be reclassified to earnings			$ 72
Term of gain or loss recognition in interest expense on terminated derivatives recorded in OCI			12 months
EUR Denominated Loan [Member]
Gain (loss) on foreign currency transaction designated as a hedge of a net investment in a foreign subsidiary	$ (664)		$ 2,150
Intercompany Loan [Member]
Gain (loss) on foreign currency transaction designated as a hedge of a net investment in a foreign subsidiary	281	$ (345)	735	$ 517
Value of Net Investment Hedging Instruments Used | ¥					¥ 160,000				¥ 160,000
Derivatives in Cash Flow Hedging Relationships [Member]
Amount of Gain (Loss) Recognized in Accumulated OCI on Derivative	$ 0	$ 0	$ 0	$ 0
Total Accumulated Other Comprehensive (Loss) Earnings [Member]
Unrecognized gains (loss)							$ 254	$ 290
2008 Note Purchase Agreement [Member]
Issuance Date			Oct. 01, 2008
2009 Note Purchase Agreement [Member]
Issuance Date			Apr. 01, 2009
2013 Note Purchase Agreement [Member]
Issuance Date			Oct. 01, 2013
Face Amount							$ 250,000
First Closing Notes [Member]
Issuance Date			Oct. 01, 2013
Second Closing Notes [Member]
Issuance Date			Nov. 15, 2013
2016 Note Purchase Agreements [Member]
Issuance Date			Sep. 23, 2016
Face Amount | €						€ 160,000
Series M Notes [Member]
Value of Net Investment Hedging Instruments Used | €						40,000
Face Amount | €						40,000
Series N Notes [Member]
Face Amount | €						77,000
Series O Notes [Member]
Face Amount | €						€ 43,000