Goodwill and Intangible Assets Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Document Period End Date	Dec. 31, 2018
Balance at September 30, 2018	$ 450,001
Acquisitions		$ 2,000
Amortization	(26,731)
Effect of foreign currency translation	(454)
Balance as of December 31, 2018	424,032
Other Acquisitions [Member]
Finite-Lived Intangible Assets [Line Items]
Acquisitions	$ 1,216