Guarantees and Commitments - Credit Quality Indicators (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Total
Total	$ 9,130,933		$ 9,130,933		$ 9,008,979
Agricultural Finance
Total
Current period charge-offs	0	$ 0	0	$ 84
Rural Infrastructure Finance
Year One
Total	450,241		450,241		741,021
Current period charge-offs	0	0	0	0
Year Two
Total	724,129		724,129		220,420
Current period charge-offs	0	0	0	0
Year Three
Total	189,385		189,385		629,223
Current period charge-offs	0	0	0	0
Year Four
Total	598,689		598,689		739,270
Current period charge-offs	0	0	0	0
Year Five
Total	711,794		711,794		7,932
Current period charge-offs	0	0	0	0
Prior
Total	610,062		610,062		649,830
Current period charge-offs	0	0	0	0
Revolving Loans - Amortized Cost Basis
Total	58,413		58,413		33,570
Current period charge-offs	0	0	0	0
Total
Total	3,342,713		3,342,713		3,021,266
Current period charge-offs	0	0	0	0
Acceptable | Rural Infrastructure Finance
Year One
Total	450,241		450,241		741,021
Year Two
Total	694,635		694,635		220,420
Year Three
Total	189,385		189,385		629,223
Year Four
Total	598,689		598,689		739,270
Year Five
Total	711,794		711,794		7,932
Prior
Total	610,062		610,062		649,830
Revolving Loans - Amortized Cost Basis
Total	58,413		58,413		33,570
Total
Total	3,313,219		3,313,219		3,021,266
Special mention | Rural Infrastructure Finance
Year One
Total	0		0		0
Year Two
Total	0		0		0
Year Three
Total	0		0		0
Year Four
Total	0		0		0
Year Five
Total	0		0		0
Prior
Total	0		0		0
Revolving Loans - Amortized Cost Basis
Total	0		0		0
Total
Total	0		0		0
Substandard | Rural Infrastructure Finance
Year One
Total	0		0		0
Year Two
Total	29,494		29,494		0
Year Three
Total	0		0		0
Year Four
Total	0		0		0
Year Five
Total	0		0		0
Prior
Total	0		0		0
Revolving Loans - Amortized Cost Basis
Total	0		0		0
Total
Total	29,494		29,494		0
Rural Infrastructure Finance:
Total
Total	3,867,746		3,867,746		3,714,184
Rural Infrastructure Finance: | Agricultural Finance
Year One
Total	148,802		148,802		202,998
Current period charge-offs	0		0	0
Year Two
Total	246,258		246,258		497,588
Current period charge-offs	0		0	0
Year Three
Total	515,135		515,135		537,752
Current period charge-offs	0		0	0
Year Four
Total	536,180		536,180		254,293
Current period charge-offs	0		0	0
Year Five
Total	273,798		273,798		212,165
Current period charge-offs	0		0	0
Prior
Total	1,295,441		1,295,441		1,183,111
Current period charge-offs	0		0	0
Revolving Loans - Amortized Cost Basis
Total	364,615		364,615		303,085
Current period charge-offs	0		0	0
Total
Total	3,380,229		3,380,229		3,190,992
Current period charge-offs	0		0	0
Rural Infrastructure Finance: | Acceptable | Agricultural Finance
Year One
Total	148,802		148,802		202,998
Year Two
Total	243,690		243,690		496,269
Year Three
Total	513,841		513,841		535,798
Year Four
Total	535,172		535,172		254,293
Year Five
Total	272,257		272,257		207,379
Prior
Total	1,228,548		1,228,548		1,107,834
Revolving Loans - Amortized Cost Basis
Total	362,825		362,825		296,508
Total
Total	3,305,135		3,305,135		3,101,079
Rural Infrastructure Finance: | Special mention | Agricultural Finance
Year One
Total	0		0		0
Year Two
Total	2,568		2,568		1,319
Year Three
Total	1,294		1,294		1,778
Year Four
Total	877		877		0
Year Five
Total	0		0		1,198
Prior
Total	39,657		39,657		42,680
Revolving Loans - Amortized Cost Basis
Total	527		527		3,205
Total
Total	44,923		44,923		50,180
Rural Infrastructure Finance: | Substandard | Agricultural Finance
Year One
Total	0		0		0
Year Two
Total	0		0		0
Year Three
Total	0		0		176
Year Four
Total	131		131		0
Year Five
Total	1,541		1,541		3,588
Prior
Total	27,236		27,236		32,597
Revolving Loans - Amortized Cost Basis
Total	1,263		1,263		3,372
Total
Total	30,171		30,171		39,733
Long-Term Standby Purchase Commitments | Rural Infrastructure Finance
Year One
Total	0		0		0
Current period charge-offs	0	0	0	0
Year Two
Total	0		0		0
Current period charge-offs	0	0	0	0
Year Three
Total	0		0		0
Current period charge-offs	0	0	0	0
Year Four
Total	0		0		0
Current period charge-offs	0	0	0	0
Year Five
Total	0		0		0
Current period charge-offs	0	0	0	0
Prior
Total	426,504		426,504		470,659
Current period charge-offs	0	0	0	0
Revolving Loans - Amortized Cost Basis
Total	61,013		61,013		52,533
Current period charge-offs	0	0	0	0
Total
Total	487,517		487,517		523,192
Current period charge-offs	0	$ 0	0	$ 0
Long-Term Standby Purchase Commitments | Acceptable | Rural Infrastructure Finance
Year One
Total	0		0		0
Year Two
Total	0		0		0
Year Three
Total	0		0		0
Year Four
Total	0		0		0
Year Five
Total	0		0		0
Prior
Total	426,504		426,504		470,659
Revolving Loans - Amortized Cost Basis
Total	61,013		61,013		52,533
Total
Total	487,517		487,517		523,192
Long-Term Standby Purchase Commitments | Special mention | Rural Infrastructure Finance
Year One
Total	0		0		0
Year Two
Total	0		0		0
Year Three
Total	0		0		0
Year Four
Total	0		0		0
Year Five
Total	0		0		0
Prior
Total	0		0		0
Revolving Loans - Amortized Cost Basis
Total	0		0		0
Total
Total	0		0		0
Long-Term Standby Purchase Commitments | Substandard | Rural Infrastructure Finance
Year One
Total	0		0		0
Year Two
Total	0		0		0
Year Three
Total	0		0		0
Year Four
Total	0		0		0
Year Five
Total	0		0		0
Prior
Total	0		0		0
Revolving Loans - Amortized Cost Basis
Total	0		0		0
Total
Total	$ 0		$ 0		$ 0