Goodwill and Other Intangible Assets - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense on intangible assets	$ 8,249	$ 5,634	$ 14,930	$ 10,575
Future amortization expense [Abstract]
Future amortization expense for the remainder 2018	17,070		17,070
Future amortization expense 2019	32,252		32,252
Future amortization expense 2020	30,425		30,425
Future amortization expense 2021	29,007		29,007
Future amortization expense 2022	$ 27,516		$ 27,516