Fair Value (Fair Value Measurements - Nonrecurring Basis) (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	$ 314,000,000	$ 108,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	19,000,000		$ 29,000,000
Loans held-for-sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	8,000,000	13,000,000	$ 0
Fair Value, measurements, nonrecurring | Automotive
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	210,000,000
Lower of cost or fair value or valuation reserve allowance	(2,000,000)
Fair Value, measurements, nonrecurring | Loans held-for-sale, Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	96,000,000
Lower of cost or fair value or valuation reserve allowance	0
Fair Value, measurements, nonrecurring | Loans held-for-sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	306,000,000	77,000,000
Lower of cost or fair value or valuation reserve allowance	(2,000,000)	0
Fair Value, measurements, nonrecurring | Commercial finance receivables and loans, automotive
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial finance receivables and loans, net, fair value	84,000,000	20,000,000
Lower of cost or fair value or valuation reserve allowance	(10,000,000)	(3,000,000)
Fair Value, measurements, nonrecurring | Commercial finance receivables and loans, other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial finance receivables and loans, net, fair value	55,000,000	22,000,000
Lower of cost or fair value or valuation reserve allowance	(46,000,000)	(12,000,000)
Fair Value, measurements, nonrecurring | Commercial loan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial finance receivables and loans, net, fair value	139,000,000	42,000,000
Lower of cost or fair value or valuation reserve allowance	(56,000,000)	(15,000,000)
Fair Value, measurements, nonrecurring | Nonmarketable equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets, fair value	1,000,000
Lower of cost or fair value or valuation reserve allowance	(1,000,000)
Fair Value, measurements, nonrecurring | Equity method investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets, fair value	3,000,000
Lower of cost or fair value or valuation reserve allowance	0
Fair Value, measurements, nonrecurring | Repossessed and foreclosed assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets, fair value	13,000,000	14,000,000
Lower of cost or fair value or valuation reserve allowance	(1,000,000)	(1,000,000)
Fair Value, measurements, nonrecurring | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets, fair value		3,000,000
Lower of cost or fair value or valuation reserve allowance		0
Fair Value, measurements, nonrecurring | Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	462,000,000	136,000,000
Lower of cost or fair value or valuation reserve allowance	(60,000,000)	(16,000,000)
Fair Value, measurements, nonrecurring | Fair value, inputs, level 1 | Automotive
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	0
Fair Value, measurements, nonrecurring | Fair value, inputs, level 1 | Loans held-for-sale, Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	0
Fair Value, measurements, nonrecurring | Fair value, inputs, level 1 | Loans held-for-sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	0	0
Fair Value, measurements, nonrecurring | Fair value, inputs, level 1 | Commercial finance receivables and loans, automotive
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial finance receivables and loans, net, fair value	0	0
Fair Value, measurements, nonrecurring | Fair value, inputs, level 1 | Commercial finance receivables and loans, other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial finance receivables and loans, net, fair value	0	0
Fair Value, measurements, nonrecurring | Fair value, inputs, level 1 | Commercial loan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial finance receivables and loans, net, fair value	0	0
Fair Value, measurements, nonrecurring | Fair value, inputs, level 1 | Nonmarketable equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets, fair value	0
Fair Value, measurements, nonrecurring | Fair value, inputs, level 1 | Equity method investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets, fair value	0
Fair Value, measurements, nonrecurring | Fair value, inputs, level 1 | Repossessed and foreclosed assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets, fair value	0	0
Fair Value, measurements, nonrecurring | Fair value, inputs, level 1 | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets, fair value		0
Fair Value, measurements, nonrecurring | Fair value, inputs, level 1 | Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	0	0
Fair Value, measurements, nonrecurring | Fair value, inputs, level 2 | Automotive
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	0
Fair Value, measurements, nonrecurring | Fair value, inputs, level 2 | Loans held-for-sale, Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	0
Fair Value, measurements, nonrecurring | Fair value, inputs, level 2 | Loans held-for-sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	0	0
Fair Value, measurements, nonrecurring | Fair value, inputs, level 2 | Commercial finance receivables and loans, automotive
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial finance receivables and loans, net, fair value	0	0
Fair Value, measurements, nonrecurring | Fair value, inputs, level 2 | Commercial finance receivables and loans, other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial finance receivables and loans, net, fair value	0	0
Fair Value, measurements, nonrecurring | Fair value, inputs, level 2 | Commercial loan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial finance receivables and loans, net, fair value	0	0
Fair Value, measurements, nonrecurring | Fair value, inputs, level 2 | Nonmarketable equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets, fair value	0
Fair Value, measurements, nonrecurring | Fair value, inputs, level 2 | Equity method investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets, fair value	0
Fair Value, measurements, nonrecurring | Fair value, inputs, level 2 | Repossessed and foreclosed assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets, fair value	0	0
Fair Value, measurements, nonrecurring | Fair value, inputs, level 2 | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets, fair value		0
Fair Value, measurements, nonrecurring | Fair value, inputs, level 2 | Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	0	0
Fair Value, measurements, nonrecurring | Fair value, inputs, level 3 | Automotive
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	210,000,000
Fair Value, measurements, nonrecurring | Fair value, inputs, level 3 | Loans held-for-sale, Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	96,000,000
Fair Value, measurements, nonrecurring | Fair value, inputs, level 3 | Loans held-for-sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	306,000,000	77,000,000
Fair Value, measurements, nonrecurring | Fair value, inputs, level 3 | Commercial finance receivables and loans, automotive
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial finance receivables and loans, net, fair value	84,000,000	20,000,000
Fair Value, measurements, nonrecurring | Fair value, inputs, level 3 | Commercial finance receivables and loans, other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial finance receivables and loans, net, fair value	55,000,000	22,000,000
Fair Value, measurements, nonrecurring | Fair value, inputs, level 3 | Commercial loan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial finance receivables and loans, net, fair value	139,000,000	42,000,000
Fair Value, measurements, nonrecurring | Fair value, inputs, level 3 | Nonmarketable equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets, fair value	1,000,000
Fair Value, measurements, nonrecurring | Fair value, inputs, level 3 | Equity method investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets, fair value	3,000,000
Fair Value, measurements, nonrecurring | Fair value, inputs, level 3 | Repossessed and foreclosed assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets, fair value	13,000,000	14,000,000
Fair Value, measurements, nonrecurring | Fair value, inputs, level 3 | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets, fair value		3,000,000
Fair Value, measurements, nonrecurring | Fair value, inputs, level 3 | Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	462,000,000	$ 136,000,000
Valuation Technique, Market Approach [Member] | Fair Value, measurements, nonrecurring | Automotive
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	104,000,000
Valuation Technique, Discounted Cash Flow [Member] | Fair Value, measurements, nonrecurring | Automotive
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	106,000,000
Minimum | Valuation Technique, Discounted Cash Flow [Member] | Fair Value, measurements, nonrecurring | Automotive
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	0.08
Maximum | Valuation Technique, Discounted Cash Flow [Member] | Fair Value, measurements, nonrecurring | Automotive
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	1.09
Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member] | Fair Value, measurements, nonrecurring | Automotive
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	$ 0.72