Acquisitions - Other Information for Fiscal 2018 Acquisitions (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2019	Dec. 31, 2018	Jun. 25, 2018	Dec. 31, 2017	Oct. 06, 2017
Business Acquisition [Line Items]
Goodwill	$ 299,248	$ 300,527	$ 296,638		$ 290,215
Acquisition related costs	$ 600
GPMX
Business Acquisition [Line Items]
Cash and cash equivalents						$ 2,560
Earning assets						17,247
Other assets						2,145
Property and equipment, intangible assets, deferred taxes and other assets, net						11,671
Goodwill						34,816
Accounts payable, deferred taxes and other liabilities						(6,723)
Total consideration						61,716
GPMX | Trade names
Business Acquisition [Line Items]
Intangible assets						$ 9,800
All Other
Business Acquisition [Line Items]
Cash and cash equivalents				$ 0
Earning assets				8,347
Other assets				3,737
Property and equipment, intangible assets, deferred taxes and other assets, net				13,678
Goodwill				7,770
Accounts payable, deferred taxes and other liabilities				1,621
Total consideration				35,153
All Other | Trade names
Business Acquisition [Line Items]
Intangible assets				$ 6,600