Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

+ Details

Name:	invest_DerivativeNotionalAmount
Namespace Prefix:	invest_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
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_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value as of the balance sheet date of the embedded derivative or group of embedded derivatives classified as a liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624163-113959

+ Details

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

- Details

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_OtherLiabilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=htlf_EmbeddedConversionOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Derivative Financial Instruments (Embedded derivatives) (Embedded conversion options) (Balance sheet category and fair values) (Details) - Other liabilities - USD ($)	Sep. 30, 2017	Dec. 31, 2016	Feb. 05, 2016
Derivative [Line Items]
Notional Amount			$ 2,000,000
Embedded conversion option
Derivative [Line Items]
Notional Amount	$ 0	$ 558,000
Fair Value	$ 0	$ 422,000