Business Segment Information (Segment Pre-Tax Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Segment Pre-tax Income (Loss)
Interest income	$ 513.6	$ 516.5
Interest expense (benefit)	225.7	235.6
Provision for credit losses	513.9	33.0
Rental income on operating leases	209.8	217.7
Other non-interest income	130.6	96.8
Depreciation on operating lease equipment	78.3	79.4
Maintenance and other operating lease expenses	53.6	49.8
Goodwill impairment	344.7
Operating expenses/loss on debt extinguishment and deposit redemption	334.4	276.2
(Loss) income from continuing operations before (benefit) provision for income taxes	(696.6)	157.0
Select Period End Balances
Loans	38,530.4	31,247.0	$ 30,998.9
Credit balances of factoring clients	(1,023.7)	(1,651.3)	(1,176.2)
Assets held for sale	73.2	79.4	32.1
Operating lease equipment, net	7,488.1	6,989.5	7,319.7
Corporate
Segment Pre-tax Income (Loss)
Interest income	44.1	64.4
Interest expense (benefit)	72.3	75.5
Other non-interest income	29.3	14.5
Operating expenses/loss on debt extinguishment and deposit redemption	19.0	1.7
(Loss) income from continuing operations before (benefit) provision for income taxes	(17.9)	1.7
Select Period End Balances
Assets held for sale		18.8
Commercial Banking
Segment Pre-tax Income (Loss)
Provision for credit losses	508.9	35.1
Goodwill impairment	301.5
Select Period End Balances
Loans	30,022.7		24,393.4
Commercial Banking | Operating Segments
Segment Pre-tax Income (Loss)
Interest income	367.9	356.6
Interest expense (benefit)	163.5	199.4
Provision for credit losses	508.9	35.1
Rental income on operating leases	209.8	217.7
Other non-interest income	87.3	77.6
Depreciation on operating lease equipment	78.3	79.4
Maintenance and other operating lease expenses	53.6	49.8
Goodwill impairment	301.5
Operating expenses/loss on debt extinguishment and deposit redemption	213.3	180.7
(Loss) income from continuing operations before (benefit) provision for income taxes	(654.1)	107.5
Select Period End Balances
Loans	30,022.7	24,641.3
Credit balances of factoring clients	(1,023.7)	(1,651.3)
Assets held for sale	48.3	56.1
Operating lease equipment, net	7,488.1	6,989.5
Consumer Banking
Segment Pre-tax Income (Loss)
Provision for credit losses	5.0	(2.1)
Goodwill impairment	43.2
Select Period End Balances
Loans	8,507.7		$ 6,605.5
Consumer Banking | Operating Segments
Segment Pre-tax Income (Loss)
Interest income	101.6	95.5
Interest expense (benefit)	(10.1)	(39.3)
Provision for credit losses	5.0	(2.1)
Other non-interest income	14.0	4.7
Goodwill impairment	43.2
Operating expenses/loss on debt extinguishment and deposit redemption	102.1	93.8
(Loss) income from continuing operations before (benefit) provision for income taxes	(24.6)	47.8
Select Period End Balances
Loans	8,507.7	6,605.7
Assets held for sale	$ 24.9	$ 4.5