Debt - Schedule of Debt (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Short Term and Long Term Debt [Line Items]
Secured debt	$ 46,170	$ 39,959
Unsecured debt	50,019	48,979
Total secured and unsecured debt	96,189	88,938
Secured debt fair value	46,073	40,160
Unsecured debt fair value	45,436	50,239
Fair value of Secured and Unsecured debt	91,509	90,399
Level 2 [Member]
Short Term and Long Term Debt [Line Items]
Fair value of Secured and Unsecured debt	89,892	88,481
Level 3 [Member]
Short Term and Long Term Debt [Line Items]
Fair value of Secured and Unsecured debt	1,617	1,918
Revolving Credit Facility [Member]
Short Term and Long Term Debt [Line Items]
Secured debt	14,289	6,152
Unsecured debt	1,970	1,936
Secured debt fair value	14,295	6,160
Unsecured debt fair value	1,962	1,936
Securitization Notes Payable [Member]
Short Term and Long Term Debt [Line Items]
Secured debt	31,881	33,807
Secured debt fair value	31,778	34,000
Senior Notes [Member]
Short Term and Long Term Debt [Line Items]
Unsecured debt	45,440	43,679
Unsecured debt fair value	40,865	44,937
Other Unsecured Debt [Member]
Short Term and Long Term Debt [Line Items]
Unsecured debt	2,609	3,364
Unsecured debt fair value	$ 2,609	$ 3,366