FAIR VALUE MEASUREMENTS, FINTECH ACQUISITION CORP. II, Gross Holding Gains and Fair Value of Held-to-maturity (FY) (Details) - USD ($)	3 Months Ended	12 Months Ended
Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash [Member]
Debt Securities, Held-to-maturity [Abstract]
Cash held in the trust account	$ 261,580	$ 6,050	$ 0
U.S. Treasury Securities [Member]
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Amortized Cost	176,156,606	175,877,136	0
Gross Holding Losses		(80,806)	0
Fair Value	$ 176,167,162	$ 175,796,330	$ 0
Maturity date	Jul. 12, 2018	Jan. 18, 2018

The total amount of cash and securities held by third party trustees pursuant to terms of debt instruments or other agreements as of the date of each statement of financial position presented, which can be used by the trustee only to pay the noncurrent portion of specified obligations.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(b))
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Amount of investment in debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity).

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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-Name Accounting Standards Codification
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Date of maturity of investment in debt security measured at amortized cost (held-to-maturity), in CCYY-MM-DD format.

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