Note 7 - Fair Value Measurement - Fair Value Quantitative Information (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2017	Dec. 31, 2016
Other Real Estate Owned [Member] \| Discounted Appraised Value [Member]
Nonrecurring assets	$ 1,378	$ 1,560
Other Real Estate Owned [Member] \| Discounted Appraised Value [Member] \| Minimum [Member]
Fair value measurements, range	6.00%	6.00%
Fair value measurements, range	4.00%	4.00%
Other Real Estate Owned [Member] \| Discounted Appraised Value [Member] \| Maximum [Member]
Fair value measurements, range	6.00%	6.00%
Fair value measurements, range	13.00%	12.00%
Other Real Estate Owned [Member] \| Discounted Appraised Value [Member] \| Weighted Average [Member]
Fair value measurements, range	6.00%	6.00%
Fair value measurements, range	12.00%	10.00%
Other Real Estate Owned [Member] \| Internal Evaluations [Member]
Nonrecurring assets	$ 2,184	$ 2,234
Other Real Estate Owned [Member] \| Internal Evaluations [Member] \| Minimum [Member]
Fair value measurements, range	4.00%	4.00%
Other Real Estate Owned [Member] \| Internal Evaluations [Member] \| Maximum [Member]
Fair value measurements, range	95.00%	54.00%
Other Real Estate Owned [Member] \| Internal Evaluations [Member] \| Weighted Average [Member]
Fair value measurements, range	22.00%	24.00%
Impaired Loans [Member] \| Discounted Appraised Value [Member]
Impaired loans		$ 98
Impaired Loans [Member] \| Discounted Appraised Value [Member] \| Minimum [Member]
Fair value measurements, range		6.00%
Impaired Loans [Member] \| Discounted Appraised Value [Member] \| Maximum [Member]
Fair value measurements, range		6.00%
Impaired Loans [Member] \| Discounted Appraised Value [Member] \| Weighted Average [Member]
Fair value measurements, range		6.00%

This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value on a nonrecurring basis by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

No definition available.

+ Details

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

- Definition

Adjustment to the discount rate used to measure fair value for lack of ability to convert business interests into cash quickly.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueInputsDiscountForLackOfMarketability
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

+ References

+ Details

Name:	us-gaap_FairValueInputsDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Cost basis of real estate investments for federal income tax purposes for entities with a substantial portion of business acquiring and holding investment real estate.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 970
-SubTopic 360
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-28.FN6)
-URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 10
-Section S99
-Paragraph 6
-Subparagraph (SX 210.5-04.(c) Schedule III)
-URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674

+ Details

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

- Details

Name:	us-gaap_FairValueByAssetClassAxis=hmta_OtherRealEstateOwnedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ValuationTechniqueAxis=hmta_DiscountedAppraisedValueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_WeightedAverageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ValuationTechniqueAxis=hmta_InternalEvaluationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByAssetClassAxis=hmta_ImpairedLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: