Debt - Schedule of Debt (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Short Term and Long Term Debt [Line Items]
Secured debt	$ 40,308	$ 39,959
Unsecured debt	51,944	48,979
Total secured and unsecured debt	92,252	88,938
Secured debt fair value	40,673	40,160
Unsecured debt fair value	52,017	50,239
Fair value of Secured and Unsecured debt	92,690	90,399
Level 2 [Member]
Short Term and Long Term Debt [Line Items]
Fair value of Secured and Unsecured debt	91,237	88,481
Level 3 [Member]
Short Term and Long Term Debt [Line Items]
Fair value of Secured and Unsecured debt	1,453	1,918
Revolving Credit Facility [Member]
Short Term and Long Term Debt [Line Items]
Secured debt	7,605	6,152
Unsecured debt	1,857	1,936
Secured debt fair value	7,608	6,160
Unsecured debt fair value	1,846	1,936
Securitization Notes Payable [Member]
Short Term and Long Term Debt [Line Items]
Secured debt	32,703	33,807
Secured debt fair value	33,065	34,000
Senior Notes [Member]
Short Term and Long Term Debt [Line Items]
Unsecured debt	46,641	43,679
Unsecured debt fair value	46,721	44,937
Other Unsecured Debt [Member]
Short Term and Long Term Debt [Line Items]
Unsecured debt	3,446	3,364
Unsecured debt fair value	$ 3,450	$ 3,366