Notes Payable - Earliest Interest Reset Date of Borrowing Outstanding (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Year two	$ 4,179,985	$ 3,004,203
Year three	2,554,906	2,809,551
Year four	2,119,805	927,119
Total principal net of discounts	$ 22,758,533	$ 21,795,677
Short-term debt, weighted average rate (as a percent)	0.45%	0.59%
Weighted - average rate (as a percent)	1.10%	1.37%
Total weighted - average rate (as a percent)	0.90%	0.98%
Due within one year
Debt Instrument [Line Items]
Due within one year	$ 8,795,560
Short-term debt, weighted average rate (as a percent)	0.43%
Year one
Debt Instrument [Line Items]
Year one	$ 3,588,630
Weighted - average rate (as a percent)	0.91%
Year two
Debt Instrument [Line Items]
Year two	$ 2,489,936
Weighted - average rate (as a percent)	0.89%
Year three
Debt Instrument [Line Items]
Year three	$ 1,859,428
Weighted - average rate (as a percent)	0.92%
Year four
Debt Instrument [Line Items]
Year four	$ 2,632,015
Weighted - average rate (as a percent)	1.10%
Thereafter
Debt Instrument [Line Items]
Thereafter	$ 3,392,964
Weighted - average rate (as a percent)	1.96%