MERGER TRANSACTION COSTS PAYABLE - Summary (FY) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Other Liabilities Disclosure [Abstract]
Merger transaction costs payable in shares	$ 0	$ 4,250	$ 0

The amount that is required to be paid, determined under the conditions specified in the contract, if as of the reporting date, the holder of the share has exercised the right to or the shares are mandatorily redeemable within one year of the reporting date or operating cycle, if longer.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 480
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481648/480-10-50-2

Name:	us-gaap_SharesSubjectToMandatoryRedemptionSettlementTermsAmountCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant