Leases - Narrative (Details) $ in Thousands	1 Months Ended	3 Months Ended			9 Months Ended		12 Months Ended
	Mar. 31, 2019 USD ($) branch property corporate_location	Sep. 30, 2019 USD ($)	Mar. 31, 2019 USD ($) branch property corporate_location	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2019 USD ($)
Sale Leaseback Transaction [Line Items]
Sales-type and direct financing leases total net investment		$ 422,004			$ 422,004
Sales-type and direct financing leases receivables		1,300			1,300
Sales-type and direct financing leases unguaranteed residuals		420,700			420,700
Lease income		5,000		$ 3,600	13,900	$ 10,800
Operating leases, ROU assets		286,014			286,014
Operating leases, liabilities		309,228			309,228
Expected lease costs		$ 9,096			$ 25,019
Lease costs				7,900		24,300
Sublease income				$ 871		$ 2,700
Sale leaseback transaction, March 2019
Sale Leaseback Transaction [Line Items]
Sale-leaseback, number of properties | property	26		26
Sale-leaseback, number of branches | branch	25		25
Sale-leaseback, number of corporate offices | corporate_location	1		1
Sale-leaseback sale price	$ 100,500
Pre-tax net gain sale-leaseback			$ 78,500
Operating leases, ROU assets	78,400		78,400
Operating leases, liabilities	$ 78,400		$ 78,400
Operating lease, term of contract	12 years		12 years
Sale leaseback transaction, March 2019 | Scenario, forecast
Sale Leaseback Transaction [Line Items]
Expected lease costs							$ 7,900