Employee Stock Ownership Plan - Additional Information (Details) - USD ($)	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Employee stock ownership plan ESOP compensation expense including mark to market adjustment amount	$ 60,000	$ 37,000
2009 ESOP [Member]
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Number of shares not yet released	355,829
Annual ESOP on the based on close price.	$ 4,199,000
Close Price	11.80
Conversion and Reorganization Plan [Member] \| 2009 ESOP [Member]
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Sale of stock, shares	354,599
Sale of stock, price per share	$ 10

Close price.

No definition available.

Name:	cull_ClosePrice
Namespace Prefix:	cull_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Employee Stock Ownership Plan ESOP Compensation Expense Including Mark to Market Adjustment Amount

+ References

No definition available.

+ Details

Name:	cull_EmployeeStockOwnershipPlanEsopCompensationExpenseIncludingMarkToMarketAdjustmentAmount
Namespace Prefix:	cull_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Fair value of unearned shares held by the employee stock ownership plan (ESOP).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 40
-Section 50
-Paragraph 1
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=109244661&loc=d3e17540-113929

+ Details

Name:	us-gaap_EmployeeStockOwnershipPlanESOPDeferredSharesFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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_EmployeeStockOwnershipPlanESOPDisclosuresLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Sum of the allocated, committed-to-be-released and suspense shares of the entity held by the plan.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 40
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109244661&loc=d3e17540-113929

+ Details

Name:	us-gaap_EmployeeStockOwnershipPlanESOPSharesInESOP
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of shares issued or sold by the subsidiary or equity method investee per stock transaction.

+ References

No definition available.

+ Details

Name:	us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Per share amount received by subsidiary or equity investee for each share of common stock issued or sold in the stock transaction.

+ References

No definition available.

+ Details

Name:	us-gaap_SaleOfStockPricePerShare
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_EmployeeStockOwnershipPlanESOPDisclosuresByPlanAxis=cull_TwoThousandAndNineEmployeeStockOwnershipPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RestructuringPlanAxis=cull_ConversionAndReorganizationPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: