Short-term Borrowings (Narrative) (Details) (USD $)	12 Months Ended
Dec. 31, 2014 credit_line	Dec. 31, 2013 credit_line
Short-term Debt [Line Items]
Number of credit lines	1htlf_NumberOfCreditLines	1htlf_NumberOfCreditLines
Borrowing capacity	$ 20,000,000.0	$ 20,000,000
Line of credit outstanding	0us-gaap_LineOfCredit	0us-gaap_LineOfCredit
Collateralized short-term borrowing under Discount Window Program	$ 73,000,000	$ 100,800,000
Retail Repurchase Agreements
Short-term Debt [Line Items]
Debt term	12 months	12 months
Revolving Credit Facility
Short-term Debt [Line Items]
Restrictive covenants, return on average assets, minimum	0.50%
Restrictive covenants, nonperforming assets to tier 1 capital and allowance for loan and lease losses	30.00%
Restrictive covenants, allowance for loan and lease losses to gross loans and leases, minimum	1.00%
Term Loan
Short-term Debt [Line Items]
Restrictive covenants, return on average assets, minimum	0.50%
Restrictive covenants, nonperforming assets to tier 1 capital and allowance for loan and lease losses	30.00%
Restrictive covenants, allowance for loan and lease losses to gross loans and leases, minimum	1.00%

Debt Instrument, Restrictive Covenants, Allowance for Loan and Lease Losses to Gross Loans and Leases, Minimum

No definition available.

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- Definition

Debt Instrument, Restrictive Covenants, Nonperforming Assets to Tier 1 Capital and Allowance For Loan and Lease Losses, Maximum

+ References

No definition available.

+ Details

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- Definition

Debt Instrument, Restrictive Covenants, Return on Average Assets, Minimum

+ References

No definition available.

+ Details

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- Definition

Number of Credit Lines

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 20, 22

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	credit
Period Type:	instant

- Definition

The carrying amount, as of the date of the latest financial statement presented, of finance receivables which are owned but transferred to serve as collateral for the payment of the related debt obligation, primarily a secured borrowing or repurchase agreement, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 30

-Section 50

-Paragraph 1A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=34720971&loc=SL6224234-111729

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Balance Type:	debit
Period Type:	instant

- Details

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