Asset-Backed Financing - Schedule Of Secured Notes With Related Maturity (Details) - Variable Interest Entity, Primary Beneficiary - Secured Debt - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Weighted average interest rate at date of issuance	2.36%	1.67%
Secured Notes Issued June 2019
Debt Instrument [Line Items]
Company issued secured notes	$ 525,000,000
Weighted average interest rate at date of issuance	2.37%
Secured Notes Issued May 2019
Debt Instrument [Line Items]
Company issued secured notes	$ 500,000,000
Weighted average interest rate at date of issuance	3.05%
Secured Notes Issued May 2015
Debt Instrument [Line Items]
Company issued secured notes	$ 500,000,000
Weighted average interest rate at date of issuance	0.88%
Secured Notes Issued January 2015
Debt Instrument [Line Items]
Company issued secured notes	$ 700,000,000
Weighted average interest rate at date of issuance	0.89%