Intangible Assets, Goodwill and Acquisitions - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2018	Sep. 30, 2018
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 629,790	$ 855,930
Accumulated Amortization	(354,505)	(565,475)
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	622,670	622,710
Accumulated Amortization	$ (352,743)	(337,800)
Customer Relationships | Minimum
Finite Lived Intangible Assets [Line Items]
Useful Life	6 years
Customer Relationships | Maximum
Finite Lived Intangible Assets [Line Items]
Useful Life	21 years
Trademarks
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 4,800	230,900
Accumulated Amortization	$ (1,499)	(227,520)
Trademarks | Minimum
Finite Lived Intangible Assets [Line Items]
Useful Life	4 years
Trademarks | Maximum
Finite Lived Intangible Assets [Line Items]
Useful Life	12 years
Noncompete Agreements
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 2,320	2,320
Accumulated Amortization	$ (263)	$ (155)
Noncompete Agreements | Minimum
Finite Lived Intangible Assets [Line Items]
Useful Life	5 years