Commitments, Contingent Liabilities and Guarantees - Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Representations and Warranties
Loss Contingencies [Line Items]
Accrued liability	$ 4.6	$ 5.7
Certain Loans \| Performance Guarantee
Loss Contingencies [Line Items]
Outstanding balance	8.0	6.2
Maximum potential amount of undiscounted future payments	7.9	6.0
Recourse liability	0.1	0.1
SBA Guaranteed Loans \| Performance Guarantee
Loss Contingencies [Line Items]
Maximum potential amount of undiscounted future payments	14.3	16.7
Recourse liability	$ 0.8	$ 0.9

Represents the amount of recourse liability as of the balance sheet date.

No definition available.

Name:	tcf_GuaranteeObligationsRecourseLiability
Namespace Prefix:	tcf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121555522&loc=d3e12069-110248

+ Details

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

- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=121555522&loc=d3e12069-110248

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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_LossContingenciesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of loss contingency liability.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349

+ Details

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- Details

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Namespace Prefix:
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- Details

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Namespace Prefix:
Data Type:	na
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- Details

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Namespace Prefix:
Data Type:	na
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- Details

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Namespace Prefix:
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