Borrowings - Farmer Mac Facility (Detail)  | 
12 Months Ended | ||||
|---|---|---|---|---|---|
| 
 Dec. 31, 2020  
USD ($)  
debt_instrument 
 | 
 Dec. 11, 2020  
USD ($) 
 | 
 Dec. 10, 2020  
USD ($) 
 | 
 Jan. 10, 2020  
USD ($) 
 | 
 Dec. 05, 2014  
USD ($) 
 | 
|
| Debt Instrument [Line Items] | |||||
| Debt instrument, loans to value ratios percentage | 60.00% | ||||
| Farmer Mac Facility | |||||
| Debt Instrument [Line Items] | |||||
| Debt instrument, face amount | $ 225,000,000.0 | $ 8,100,000 | $ 125,000,000.0 | ||
| Number of debt instruments issued | debt_instrument | 3 | ||||
| Bonds repaid | $ 22,000,000.0 | ||||
| Interest rate (as percent) | 2.66% | ||||
| Debt instrument, loans to value ratios percentage | 60.00% | ||||
| Farmer Mac Facility | Lease One | |||||
| Debt Instrument [Line Items] | |||||
| Debt instrument, face amount | $ 3,180,000 | ||||
| Interest rate (as percent) | 2.13% | ||||
| Farmer Mac Facility | Lease Two | |||||
| Debt Instrument [Line Items] | |||||
| Debt instrument, face amount | $ 10,673,000 | ||||
| Interest rate (as percent) | 3.25% | 
| X | ||||||||||
- Definition Debt Instrument, Loans To Value Ratios Percentage No definition available. 
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- Definition Debt Instruments, Number of Debt Instruments Issued No definition available. 
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- Definition Face (par) amount of debt instrument at time of issuance. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Contractual interest rate for funds borrowed, under the debt agreement. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
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- Definition Gross amount of debt extinguished. No definition available. 
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- Details 
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- Details 
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