Loans and Allowance for Losses - Schedule of Impaired Financing Receivables (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Financing Receivable, Impaired [Line Items]
Impaired Loans, With so specific allowance, Recorded investment	$ 52,935		$ 52,935		$ 32,012
Impaired Loans, With so specific allowance, Unpaid principal balance	52,772		52,772		31,854
Impaired Loan, With a specific allowance, Recorded investment	168,477		168,477		123,300
Impaired Loans, With a specific allowance, Unpaid principal balance	167,983		167,983		122,786
Impaired Loans, Associated allowance	4,792		4,792		3,405
Recorded investment	221,412		221,412		155,312
Unpaid principal balance	220,755		220,755		154,640
Recorded investment of loans on nonaccrual status	92,287		92,287		61,408
Average recorded investment in impaired loans	196,914	$ 154,151	173,943	$ 150,716
Income recognized on impaired loans	536	1,334	2,196	2,973
Less than 90 days past due [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment of loans on nonaccrual status	36,300		36,300		41,800
Crops [Member]
Financing Receivable, Impaired [Line Items]
Impaired Loans, With so specific allowance, Recorded investment	29,146		29,146		20,734
Impaired Loans, With so specific allowance, Unpaid principal balance	29,055		29,055		20,632
Impaired Loan, With a specific allowance, Recorded investment	84,808		84,808		59,335
Impaired Loans, With a specific allowance, Unpaid principal balance	84,558		84,558		59,098
Impaired Loans, Associated allowance	2,576		2,576		1,606
Recorded investment	113,954		113,954		80,069
Unpaid principal balance	113,613		113,613		79,730
Recorded investment of loans on nonaccrual status	34,543		34,543		26,611
Average recorded investment in impaired loans	106,535	75,920	93,088	73,968
Income recognized on impaired loans	178	223	879	942
Permanent Plantings [Member]
Financing Receivable, Impaired [Line Items]
Impaired Loans, With so specific allowance, Recorded investment	16,721		16,721		3,592
Impaired Loans, With so specific allowance, Unpaid principal balance	16,669		16,669		3,573
Impaired Loan, With a specific allowance, Recorded investment	34,781		34,781		38,176
Impaired Loans, With a specific allowance, Unpaid principal balance	34,678		34,678		38,009
Impaired Loans, Associated allowance	1,114		1,114		1,134
Recorded investment	51,502		51,502		41,768
Unpaid principal balance	51,347		51,347		41,582
Recorded investment of loans on nonaccrual status	24,425		24,425		21,349
Average recorded investment in impaired loans	45,197	44,818	41,524	44,122
Income recognized on impaired loans	166	933	586	1,597
Livestock [Member]
Financing Receivable, Impaired [Line Items]
Impaired Loans, With so specific allowance, Recorded investment	4,771		4,771		5,764
Impaired Loans, With so specific allowance, Unpaid principal balance	4,758		4,758		5,737
Impaired Loan, With a specific allowance, Recorded investment	42,686		42,686		19,443
Impaired Loans, With a specific allowance, Unpaid principal balance	42,563		42,563		19,361
Impaired Loans, Associated allowance	983		983		522
Recorded investment	47,457		47,457		25,207
Unpaid principal balance	47,321		47,321		25,098
Recorded investment of loans on nonaccrual status	30,213		30,213		8,803
Average recorded investment in impaired loans	36,859	24,443	31,189	23,358
Income recognized on impaired loans	87	122	504	261
Part-Time Farm [Member]
Financing Receivable, Impaired [Line Items]
Impaired Loans, With so specific allowance, Recorded investment	2,240		2,240		1,922
Impaired Loans, With so specific allowance, Unpaid principal balance	2,233		2,233		1,912
Impaired Loan, With a specific allowance, Recorded investment	6,202		6,202		6,276
Impaired Loans, With a specific allowance, Unpaid principal balance	6,184		6,184		6,249
Impaired Loans, Associated allowance	119		119		142
Recorded investment	8,442		8,442		8,198
Unpaid principal balance	8,417		8,417		8,161
Recorded investment of loans on nonaccrual status	3,106		3,106		4,645
Average recorded investment in impaired loans	8,265	8,898	8,079	8,874
Income recognized on impaired loans	105	56	227	173
Agriculture Storage and Processing [Member]
Financing Receivable, Impaired [Line Items]
Impaired Loans, With so specific allowance, Recorded investment	0		0		0
Impaired Loans, With so specific allowance, Unpaid principal balance	0		0		0
Impaired Loan, With a specific allowance, Recorded investment	0		0		0
Impaired Loans, With a specific allowance, Unpaid principal balance	0		0		0
Impaired Loans, Associated allowance	0		0		0
Recorded investment	0		0		0
Unpaid principal balance	0		0		0
Recorded investment of loans on nonaccrual status	0		0		0
Average recorded investment in impaired loans	0	0	0	0
Income recognized on impaired loans	0	0	0	0
Other Commodity [Member]
Financing Receivable, Impaired [Line Items]
Impaired Loans, With so specific allowance, Recorded investment	57		57		0
Impaired Loans, With so specific allowance, Unpaid principal balance	57		57		0
Impaired Loan, With a specific allowance, Recorded investment	0		0		70
Impaired Loans, With a specific allowance, Unpaid principal balance	0		0		69
Impaired Loans, Associated allowance	0		0		1
Recorded investment	57		57		70
Unpaid principal balance	57		57		69
Recorded investment of loans on nonaccrual status	0		0		0
Average recorded investment in impaired loans	58	72	63	394
Income recognized on impaired loans	0	$ 0	0	$ 0
Collateral Dependent Not Individually Analyzed [Member]
Financing Receivable, Impaired [Line Items]
Impaired Loans, Associated allowance	3,400		3,400		2,700
Recorded investment	$ 166,100		$ 166,100		$ 120,900
Impaired loans, impairment analysis performed percent	75.00%		75.00%		78.00%