Derivative Financial Instruments - Interest Rate Swaps (Details) - USD ($)	Jun. 30, 2025	Dec. 31, 2024
Derivative [Line Items]
Notional amount		$ 165,000,000
Interest rate swaps - intercompany deposits
Derivative [Line Items]
Notional amount	$ 195,000,000
Weighted average fixed rate paid by the Company	3.50%	3.44%
2028
Derivative [Line Items]
Notional amount	$ 40,000,000	$ 40,000,000
Weighted average fixed rate paid by the Company	3.33%	3.33%
2029
Derivative [Line Items]
Notional amount	$ 25,000,000	$ 25,000,000
Weighted average fixed rate paid by the Company	3.37%	3.37%
2030
Derivative [Line Items]
Notional amount	$ 50,000,000	$ 50,000,000
Weighted average fixed rate paid by the Company	3.06%	3.06%
Interest Rate Swap, Nelnet Bank, 2030 With Forward Effective Date Of April 2026
Derivative [Line Items]
Notional amount	$ 25,000,000	$ 25,000,000
Interest Rate Swap, Nelnet Bank, 2030 With Forward Effective Date Of May 2026
Derivative [Line Items]
Notional amount	25,000,000	25,000,000
2032
Derivative [Line Items]
Notional amount	$ 25,000,000	$ 25,000,000
Weighted average fixed rate paid by the Company	4.03%	4.03%
2033
Derivative [Line Items]
Notional amount	$ 25,000,000	$ 25,000,000
Weighted average fixed rate paid by the Company	3.90%	3.90%
2035
Derivative [Line Items]
Notional amount	$ 30,000,000	$ 0
Weighted average fixed rate paid by the Company	3.79%	0.00%