Goodwill and Intangible Assets Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2017	Sep. 30, 2017
Finite-Lived Intangible Assets [Line Items]
Document Period End Date	Dec. 31, 2017
Finite-lived Intangible Assets Acquired	$ 2,000
Finite-Lived Intangible Assets, Purchase Accounting Adjustments	0
Goodwill	$ 3,600,768	$ 3,590,608