Loans - Schedule of Financing Receivables Credit Quality Indicators (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Total
Total	$ 7,148,108
Total	7,148,108
90-Days Delinquencies	29,997
Farm & Ranch
2020
Total	296,887
Current period charge-offs	0
Current period recoveries	0
Current period net charge-offs	0
2019
Total	983,174
Current period charge-offs	0
Current period recoveries	0
Current period net charge-offs	0
2018
Total	642,485
Current period charge-offs	0
Current period recoveries	0
Current period net charge-offs	0
2017
Total	767,993
Current period charge-offs	0
Current period recoveries	0
Current period net charge-offs	0
2016
Total	629,878
Current period charge-offs	0
Current period recoveries	0
Current period net charge-offs	0
Prior
Total	1,549,183
Current period charge-offs	0
Current period recoveries	0
Current period net charge-offs	0
Revolving Loans - Amortized Cost Basis
Total	488,782
Current period charge-offs	0
Current period recoveries	0
Current period net charge-offs	0
Total
Total	5,358,382
Current period charge-offs	0	$ 0
Current period recoveries	0
Current period net charge-offs	0
Total	5,358,382
90-Days Delinquencies	29,997
Rural  Utilities
2020
Total	152,385
Current period charge-offs	0
Current period recoveries	0
Current period net charge-offs	0
2019
Total	836,763
Current period charge-offs	0
Current period recoveries	0
Current period net charge-offs	0
2018
Total	8,337
Current period charge-offs	0
Current period recoveries	0
Current period net charge-offs	0
2017
Total	92,568
Current period charge-offs	0
Current period recoveries	0
Current period net charge-offs	0
2016
Total	31,829
Current period charge-offs	0
Current period recoveries	0
Current period net charge-offs	0
Prior
Total	667,844
Current period charge-offs	0
Current period recoveries	0
Current period net charge-offs	0
Revolving Loans - Amortized Cost Basis
Total	0
Current period charge-offs	0
Current period recoveries	0
Current period net charge-offs	0
Total
Total	1,789,726
Current period charge-offs	0	$ 0
Current period recoveries	0
Current period net charge-offs	0
Total	1,789,726
90-Days Delinquencies	0
Acceptable | Farm & Ranch
2020
Total	286,971
2019
Total	819,220
2018
Total	588,761
2017
Total	688,649
2016
Total	555,678
Prior
Total	1,452,711
Revolving Loans - Amortized Cost Basis
Total	468,114
Total
Total	4,860,104
Total	4,860,104
Acceptable | Rural  Utilities
2020
Total	152,385
2019
Total	836,763
2018
Total	8,337
2017
Total	92,568
2016
Total	31,829
Prior
Total	662,830
Revolving Loans - Amortized Cost Basis
Total	0
Total
Total	1,784,712
Total	1,784,712
Special mention(1) | Farm & Ranch
2020
Total	9,916
2019
Total	159,523
2018
Total	36,786
2017
Total	20,937
2016
Total	32,227
Prior
Total	18,283
Revolving Loans - Amortized Cost Basis
Total	9,230
Total
Total	286,902
Total	286,902
Special mention(1) | Rural  Utilities
2020
Total	0
2019
Total	0
2018
Total	0
2017
Total	0
2016
Total	0
Prior
Total	0
Revolving Loans - Amortized Cost Basis
Total	0
Total
Total	0
Total	0
Substandard(2) | Farm & Ranch
2020
Total	0
2019
Total	4,431
2018
Total	16,938
2017
Total	58,407
2016
Total	41,973
Prior
Total	78,189
Revolving Loans - Amortized Cost Basis
Total	11,438
Total
Total	211,376
Total	211,376
Substandard(2) | Rural  Utilities
2020
Total	0
2019
Total	0
2018
Total	0
2017
Total	0
2016
Total	0
Prior
Total	5,014
Revolving Loans - Amortized Cost Basis
Total	0
Total
Total	5,014
Total	$ 5,014
On-Balance Sheet:
Total
Total			$ 5,276,557
Total			5,276,557
90-Days Delinquencies			57,719
On-Balance Sheet: | Acceptable
Total
Total			4,790,636
Total			4,790,636
On-Balance Sheet: | Special mention(1)
Total
Total			278,843
Total			278,843
On-Balance Sheet: | Substandard(2)
Total
Total			207,078
Total			207,078
On-Balance Sheet: | Crops
Total
Total			2,773,177
Total			2,773,177
90-Days Delinquencies			21,167
On-Balance Sheet: | Crops | Acceptable
Total
Total			2,556,956
Total			2,556,956
On-Balance Sheet: | Crops | Special mention(1)
Total
Total			107,406
Total			107,406
On-Balance Sheet: | Crops | Substandard(2)
Total
Total			108,815
Total			108,815
On-Balance Sheet: | Permanent Plantings
Total
Total			1,213,156
Total			1,213,156
90-Days Delinquencies			15,828
On-Balance Sheet: | Permanent Plantings | Acceptable
Total
Total			1,050,160
Total			1,050,160
On-Balance Sheet: | Permanent Plantings | Special mention(1)
Total
Total			111,739
Total			111,739
On-Balance Sheet: | Permanent Plantings | Substandard(2)
Total
Total			51,257
Total			51,257
On-Balance Sheet: | Livestock
Total
Total			911,303
Total			911,303
90-Days Delinquencies			19,354
On-Balance Sheet: | Livestock | Acceptable
Total
Total			825,234
Total			825,234
On-Balance Sheet: | Livestock | Special mention(1)
Total
Total			46,107
Total			46,107
On-Balance Sheet: | Livestock | Substandard(2)
Total
Total			39,962
Total			39,962
On-Balance Sheet: | Part-time Farm
Total
Total			363,964
Total			363,964
90-Days Delinquencies			1,370
On-Balance Sheet: | Part-time Farm | Acceptable
Total
Total			343,329
Total			343,329
On-Balance Sheet: | Part-time Farm | Special mention(1)
Total
Total			13,591
Total			13,591
On-Balance Sheet: | Part-time Farm | Substandard(2)
Total
Total			7,044
Total			7,044
On-Balance Sheet: | Ag. Storage and Processing
Total
Total			10,360
Total			10,360
90-Days Delinquencies			0
On-Balance Sheet: | Ag. Storage and Processing | Acceptable
Total
Total			10,360
Total			10,360
On-Balance Sheet: | Ag. Storage and Processing | Special mention(1)
Total
Total			0
Total			0
On-Balance Sheet: | Ag. Storage and Processing | Substandard(2)
Total
Total			0
Total			0
On-Balance Sheet: | Other
Total
Total			4,597
Total			4,597
90-Days Delinquencies			0
On-Balance Sheet: | Other | Acceptable
Total
Total			4,597
Total			4,597
On-Balance Sheet: | Other | Special mention(1)
Total
Total			0
Total			0
On-Balance Sheet: | Other | Substandard(2)
Total
Total			0
Total			$ 0