Debt - Schedule of Debt (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Short Term and Long Term Debt [Line Items]
Secured debt	$ 35,671	$ 39,959
Unsecured debt	53,151	48,979
Total secured and unsecured debt	88,822	88,938
Secured debt fair value	36,108	40,160
Unsecured debt fair value	54,226	50,239
Fair value of Secured and Unsecured debt	90,334	90,399
Level 2 [Member]
Short Term and Long Term Debt [Line Items]
Fair value of Secured and Unsecured debt	88,768	88,481
Level 3 [Member]
Short Term and Long Term Debt [Line Items]
Fair value of Secured and Unsecured debt	1,566	1,918
Revolving Credit Facility [Member]
Short Term and Long Term Debt [Line Items]
Secured debt	2,048	6,152
Unsecured debt	1,417	1,936
Secured debt fair value	2,050	6,160
Unsecured debt fair value	1,415	1,936
Securitization Notes Payable [Member]
Short Term and Long Term Debt [Line Items]
Secured debt	33,623	33,807
Secured debt fair value	34,058	34,000
Senior Notes [Member]
Short Term and Long Term Debt [Line Items]
Unsecured debt	47,935	43,679
Unsecured debt fair value	49,008	44,937
Other Unsecured Debt [Member]
Short Term and Long Term Debt [Line Items]
Unsecured debt	3,799	3,364
Unsecured debt fair value	$ 3,803	$ 3,366