Goodwill and Other Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018	Mar. 14, 2018	Sep. 30, 2017	Aug. 30, 2017	May 25, 2017	May 08, 2017	Nov. 07, 2016
Goodwill and Other Intangible Assets
Goodwill	$ 409,215	$ 381,652	$ 3,500	$ 377,900	$ 10,700	$ 4,800	$ 7,500	$ 30,100
Patents
Goodwill and Other Intangible Assets
Gross carrying amount	2,100	1,800
Less: accumulated amortization	900	800
Net	1,200	1,000
Capitalized software
Goodwill and Other Intangible Assets
Gross carrying amount	79,700	71,300
Less: accumulated amortization	49,200	41,600
Net	30,500	29,700
Customer relationships
Goodwill and Other Intangible Assets
Gross carrying amount	241,300	185,300
Less: accumulated amortization	59,000	47,800
Net	182,300	137,500
Other
Goodwill and Other Intangible Assets
Gross carrying amount	5,300	5,500
Less: accumulated amortization	2,600	2,000
Net	2,700	3,500
Trade names
Goodwill and Other Intangible Assets
Trade names	$ 176,300	$ 173,700