v3.26.1
Investments and Notes Receivable - Schedule of Investments (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Marketable Securities [Line Items]          
Amortized cost $ 1,580,863   $ 1,580,863    
Fair value 1,578,340   1,578,340    
Equity securities and funds measured at net asset value 123,052   123,052   $ 109,648
Total investments at fair value 1,701,392   1,701,392   1,414,636
Fair value 210,908   210,908    
Beneficial interest in securitizations 188,852   188,852   194,830
Notes receivable 41,772   41,772   32,085
Other investments and notes receivable, net 967,352   967,352   933,335
Total investments and notes receivable 2,668,744   2,668,744   2,347,971
Investments - beneficial interest in loan securitizations 2,400 $ 5,000 6,600 $ 6,500  
Less: losses attributable to noncontrolling members (21,191) (3,605) (36,717) (5,035)  
Net (loss) gain attributable to the Company 66,662 181,459 137,788 264,018  
Venture capital, funds, and other:          
Marketable Securities [Line Items]          
Measurement alternative 236,062   236,062   227,962
Equity method 258,331   258,331   248,253
Other investments 494,393   494,393   476,215
Real estate equity method          
Marketable Securities [Line Items]          
Equity method 272,713   272,713   233,167
Partnership Interest          
Marketable Securities [Line Items]          
Equity method 0   0   0
Other investments 23,500   23,500   10,148
Preferred membership interest 23,500   23,500   10,148
Consumer Loan and private education loans          
Marketable Securities [Line Items]          
Beneficial interest in securitizations 173,752   173,752   180,262
Beneficial interest in securitization, allowance for credit losses (55,123)   (55,123)   (50,802)
Consumer loans - Nelnet Bank          
Marketable Securities [Line Items]          
Loans corresponding to beneficial interest 950,000   950,000    
Beneficial interest in federally insured loan securitizations          
Marketable Securities [Line Items]          
Beneficial interest in securitizations 15,100   15,100   14,568
Loans corresponding to beneficial interest 280,000   280,000    
Solar          
Marketable Securities [Line Items]          
Solar (286,992)   (286,992)   (240,370)
Amount funded or committed to fund 367,600   367,600    
Amount funded or committed to fund by partners 469,700   469,700    
Tax credits by partners 423,100   423,100    
Carrying value (287,000)   (287,000)    
Equity method investment attributable to parent (131,400)   (131,400)    
Losses from HLBV accounting (gross) (29,351) (6,463) (51,882) (9,079)  
Gains from sales (gross) 6,854 4,961 6,854 8,033  
Losses from solar investments (gross) (22,497) (1,502) (45,028) (1,046)  
Less: losses attributable to noncontrolling members (19,491) (3,159) (32,936) (4,204)  
Net (loss) gain attributable to the Company (3,006) $ 1,657 (12,092) $ 3,158  
Solar | Third-Party Co-Investors          
Marketable Securities [Line Items]          
Tax credits by partners 464,200   464,200    
Tax liens, affordable housing, and other          
Marketable Securities [Line Items]          
Other investments 22,206   22,206   15,961
Beneficial interest in private education loan securitizations          
Marketable Securities [Line Items]          
Loans corresponding to beneficial interest 350,000   350,000    
FFELP loan          
Marketable Securities [Line Items]          
Amortized cost 43,466   43,466   36,824
Gross unrealized gains 2,878   2,878   2,950
Gross unrealized losses (146)   (146)   (129)
Fair value 46,198   46,198   39,645
FFELP loan and other debt securities - restricted          
Marketable Securities [Line Items]          
Amortized cost 192,387   192,387   172,739
Gross unrealized gains 3,045   3,045   3,384
Gross unrealized losses (662)   (662)   (323)
Fair value 194,770   194,770   175,800
Private education loan          
Marketable Securities [Line Items]          
Amortized cost 177,299   177,299   197,568
Gross unrealized gains 90   90   20
Gross unrealized losses (12,258)   (12,258)   (13,436)
Fair value 165,131   165,131   184,152
Other debt securities          
Marketable Securities [Line Items]          
Amortized cost 114,801   114,801   55,874
Gross unrealized gains 2,628   2,628   2,528
Gross unrealized losses (70)   (70)   0
Fair value 117,359   117,359   58,402
Total Non-Nelnet Bank          
Marketable Securities [Line Items]          
Amortized cost 527,953   527,953   463,005
Gross unrealized gains 8,641   8,641   8,882
Gross unrealized losses (13,136)   (13,136)   (13,888)
Fair value 523,458   523,458   457,999
FFELP loan          
Marketable Securities [Line Items]          
Amortized cost 244,004   244,004   258,208
Gross unrealized gains 6,109   6,109   6,513
Gross unrealized losses (778)   (778)   (798)
Fair value 249,335   249,335   263,923
Private education loan          
Marketable Securities [Line Items]          
Amortized cost 11,815   11,815   13,623
Gross unrealized gains 0   0   0
Gross unrealized losses (35)   (35)   (37)
Fair value 11,780   11,780   13,586
Other debt securities          
Marketable Securities [Line Items]          
Amortized cost 797,091   797,091   569,528
Gross unrealized gains 721   721   1,433
Gross unrealized losses (4,045)   (4,045)   (1,481)
Fair value 793,767   793,767   569,480
Total Nelnet Bank          
Marketable Securities [Line Items]          
Amortized cost 1,052,910   1,052,910   841,359
Gross unrealized gains 6,830   6,830   7,946
Gross unrealized losses (4,858)   (4,858)   (2,316)
Fair value 1,054,882   1,054,882   846,989
Total available-for-sale asset-backed securities          
Marketable Securities [Line Items]          
Amortized cost 1,580,863   1,580,863   1,304,364
Gross unrealized gains 15,471   15,471   16,828
Gross unrealized losses (17,994)   (17,994)   (16,204)
Fair value 1,578,340   1,578,340   1,304,988
FFELP loan          
Marketable Securities [Line Items]          
Fair value 210,908   210,908   $ 211,299
Asset-Backed Securities, Available-For-Sale, Private Education Loans, Non-Nelnet Bank, Bonds          
Marketable Securities [Line Items]          
Fair value 164,900   164,900    
Bond securities, par value $ 177,100   $ 177,100