Notes Payable - Borrowings (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Due within one year:
Outstanding, Amount	$ 7,956,215	$ 8,034,175
Outstanding, Weighted - average rate (as a percent)	3.30%	2.31%
Medium-term notes due in:
Two years	$ 5,231,168
Three years	3,243,230
Four years	3,297,724
Five years	2,306,430
Thereafter	3,567,720
Total due after one year	17,646,272
Total principal net of discounts	25,602,487	$ 25,000,199
Hedging adjustments	(478,942)	(531,086)
Total	$ 25,123,545	24,469,113
Weighted - average rate (as a percent)	2.90%
Total weighted - average rate (as a percent)	3.03%
Two years
Medium-term notes due in:
Weighted - average rate (as a percent)	3.05%
Three years
Medium-term notes due in:
Weighted - average rate (as a percent)	2.21%
Four years
Medium-term notes due in:
Weighted - average rate (as a percent)	2.64%
Five years
Medium-term notes due in:
Weighted - average rate (as a percent)	4.07%
Thereafter
Medium-term notes due in:
Weighted - average rate (as a percent)	2.80%
Discount notes
Due within one year:
Outstanding, Amount	$ 1,535,856	$ 565,578
Outstanding, Weighted - average rate (as a percent)	5.30%	3.91%
Average Outstanding, Amount	$ 942,297	$ 1,325,026
Average Outstanding, Weighted - average rate (as a percent)	4.92%	0.96%
Medium-term notes
Due within one year:
Outstanding, Amount	$ 947,466	$ 2,547,733
Outstanding, Weighted - average rate (as a percent)	4.75%	3.54%
Average Outstanding, Amount	$ 2,085,249	$ 1,442,932
Average Outstanding, Weighted - average rate (as a percent)	4.00%	2.11%
Medium-term notes due in:
Two years		$ 4,072,740
Three years		3,506,480
Four years		2,967,625
Five years		2,361,197
Thereafter		4,057,982
Total due after one year		$ 16,966,024
Weighted - average rate (as a percent)		2.15%
Total weighted - average rate (as a percent)		2.20%
Medium-term notes | Two years
Medium-term notes due in:
Weighted - average rate (as a percent)		1.71%
Medium-term notes | Three years
Medium-term notes due in:
Weighted - average rate (as a percent)		2.10%
Medium-term notes | Four years
Medium-term notes due in:
Weighted - average rate (as a percent)		1.44%
Medium-term notes | Five years
Medium-term notes due in:
Weighted - average rate (as a percent)		3.12%
Medium-term notes | Thereafter
Medium-term notes due in:
Weighted - average rate (as a percent)		2.60%
Current portion of medium-term notes
Due within one year:
Outstanding, Amount	$ 5,472,893	$ 4,920,864
Outstanding, Weighted - average rate (as a percent)	2.49%	1.49%