XML 40 R65.htm IDEA: XBRL DOCUMENT
v3.19.3

Major Customer (Details) - USD ($) $ in Thousands | 3 Months Ended | 8 Months Ended | 9 Months Ended
--- | --- | --- | ---
Sep. 30, 2019 | Sep. 30, 2018 | Sep. 30, 2018 | Sep. 30, 2019 | Sep. 30, 2018
Government servicing - Nelnet |  |  |  |  |
Concentration Risk [Line Items] |  |  |  |  |
Revenue | $ 38,645 | $ 38,907 |  | $ 118,744 | $ 118,015
Government servicing - Nelnet | Customer concentration risk |  |  |  |  |
Concentration Risk [Line Items] |  |  |  |  |
Revenue | 38,600 | 38,900 |  | 118,700 | 118,000
Government servicing - Great Lakes |  |  |  |  |
Concentration Risk [Line Items] |  |  |  |  |
Revenue | 46,234 | 45,671 |  | 139,285 | $ 122,107
Government servicing - Great Lakes | Customer concentration risk |  |  |  |  |
Concentration Risk [Line Items] |  |  |  |  |
Revenue | $ 46,200 | $ 45,700 | $ 122,100 | $ 139,300 |

X
- 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. + References No definition available. + Details
Name: | us-gaap_ConcentrationRiskLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045 + Details
Name: | us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | srt_ProductOrServiceAxis=nni_GovernmentServicingNelnetMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConcentrationRiskByTypeAxis=us-gaap_CustomerConcentrationRiskMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=nni_GovernmentServicingGreatLakesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |