XML 50 R40.htm IDEA: XBRL DOCUMENT
v3.25.3

Investments - Schedule of Held To Maturity Securities by Contractual Maturity (Details) - USD ($) | Sep. 30, 2025 | Dec. 31, 2024
--- | --- | ---
Net Investment Income [Line Items] |  |
Cost or Amortized Cost | $ 6,043,708 | $ 7,047,342
Estimated Fair Value | 5,174,675 | 5,959,265
Less than one year |  |
Net Investment Income [Line Items] |  |
Cost or Amortized Cost | 0 | 499,719
Estimated Fair Value | 0 | 499,065
One to five years |  |
Net Investment Income [Line Items] |  |
Cost or Amortized Cost | 2,059,969 | 622,375
Estimated Fair Value | 2,018,138 | 600,288
Five to ten years |  |
Net Investment Income [Line Items] |  |
Cost or Amortized Cost | 0 | 1,427,579
Estimated Fair Value | 0 | 1,323,600
More than 10 years |  |
Net Investment Income [Line Items] |  |
Cost or Amortized Cost | 3,983,739 | 4,497,669
Estimated Fair Value | $ 3,156,537 | $ 3,536,312

X
- Definition [Amortized cost] + References No definition available. + Details
Name: | king_AmortizedCostHeldToMaturitySecurities
Namespace Prefix: | king_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Estimated Fair Value 3 + References No definition available. + Details
Name: | king_EstimatedFairValue3
Namespace Prefix: | king_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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 Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(2)(a)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147477250/944-220-S99-1 + Details
Name: | us-gaap_ScheduleOfInvestmentIncomeReportedAmountsByCategoryLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=king_LessThanOneYearMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=king_OneToFiveYearsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=king_FiveToTenYearsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=king_MoreThan10YearsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |