Mortgage Loans Serviced for Others, Amount

No definition available.

Name:	htlf_MortgageLoansServicedForOthersAmount
Namespace Prefix:	htlf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Servicing Asset, Agreement Term

+ References

No definition available.

+ Details

Name:	htlf_ServicingAssetAgreementTerm
Namespace Prefix:	htlf_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Valuation servicing rights in tranches [Line Items]

+ References

No definition available.

+ Details

Name:	htlf_ValuationServicingRightsInTranchesLineItems
Namespace Prefix:	htlf_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The designation of funds furnished by a borrower to a lender to assure future payments of the borrower's real estate taxes and insurance obligations with respect to a mortgaged property. Escrow deposits may be made for a variety of other purposes such as earnest money and contingent payments. This element excludes replacement reserves which are an escrow separately provided for within the US GAAP taxonomy.

+ 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 210.9-03.10)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- Definition

Ratio of the net operating income produced by an asset and its capital cost (original prices paid to buy the asset), used as an input to measure fair value.

+ 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_FairValueInputsCapRate
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

Rate at which loans or a loan portfolio are expected to prepay principal balances, used as an input to measure fair value.

+ References

+ Details

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

- Definition

Income from mortgage banking activities (fees and commissions) and servicing real estate mortgages, credit cards, and other financial assets held by others net of any related impairment of capitalized service costs. Also includes any premiums received in lieu of regular servicing fees on such loans only as earned over the life of the loans.

+ References

No definition available.

+ Details

Name:	us-gaap_FeesAndCommissionsMortgageBankingAndServicing
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Aggregate amount of servicing assets that are subsequently measured at fair value and servicing assets that are subsequently measured using the amortization method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745

+ Details

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

- Definition

Fair value of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122739-111746

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=7516967&loc=d3e66267-113978

+ Details

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

- Definition

Amount of increase (decrease) in the amortized amount from a decrease (increase) in the valuation allowance applied to the servicing asset for a contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

+ References

+ Details

Name:	us-gaap_ServicingAssetAtAmortizedValueValuationAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=htlf_MortgageServicingRightsMember
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_FiniteLivedIntangibleAssetsByMajorClassAxis=htlf_MortgageServicingRights15YearTrancheMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=htlf_MortgageServicingRights30YearTrancheMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=htlf_CommercialServicingRightsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=htlf_CommercialServicingRightslessthan20YearsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=htlf_CommercialServicingRightsmorethan20YearsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Goodwill, Core Deposit Premium and Other Intangible Assets (Mortgage and commercial loans servicing) (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Valuation servicing rights in tranches [Line Items]
Mortgage loans serviced for others	$ 4,340,000,000		$ 4,340,000,000		$ 4,310,000,000
Custodial escrow balances maintained	25,800,000		25,800,000		21,400,000
Loans serviced	34,736,000		34,736,000		35,778,000
Mortgage Servicing Rights
Valuation servicing rights in tranches [Line Items]
Servicing asset at amortized value	43,600,000	$ 39,881,000	$ 43,600,000	$ 39,881,000	$ 45,200,000
Prepayment rate			10.30%		9.63%
Discount rate			9.25%		9.26%
Fees collected for servicing of mortgage loans	3,200,000	3,000,000	$ 6,400,000	$ 5,900,000
Mortgage Servicing Rights \| Minimum
Valuation servicing rights in tranches [Line Items]
Average cap rate			0.94%	0.88%
Mortgage Servicing Rights \| Maximum
Valuation servicing rights in tranches [Line Items]
Average cap rate			1.50%	1.35%
Mortgage Servicing Rights 15-year Tranche
Valuation servicing rights in tranches [Line Items]
Servicing asset, agreement term			15 years
Mortgage Servicing Rights 30-year Tranche
Valuation servicing rights in tranches [Line Items]
Servicing asset, agreement term			30 years
Commercial Servicing Rights
Valuation servicing rights in tranches [Line Items]
Servicing asset at amortized value	3,678,000		$ 3,678,000		$ 4,800,000
Fees collected for servicing of mortgage loans			791,000	$ 455,000
Loans serviced	149,200,000		$ 149,200,000		$ 164,600,000
Commercial Servicing Rights \| Minimum
Valuation servicing rights in tranches [Line Items]
Prepayment rate			6.68%		6.96%
Discount rate			12.15%		12.44%
Average cap rate			3.10%	3.10%
Commercial Servicing Rights \| Maximum
Valuation servicing rights in tranches [Line Items]
Prepayment rate			7.78%		7.88%
Discount rate			13.72%		13.88%
Average cap rate			4.45%	4.45%
Commercial Servicing Rights Less Than 20 Years
Valuation servicing rights in tranches [Line Items]
Servicing asset at amortized value	1,026,000		$ 1,026,000		$ 1,200,000
Servicing asset, agreement term			20 years
Fees collected for servicing of mortgage loans	376,000	$ 375,000
Valuation allowance			$ 0		0
Commercial Servicing Rights More Than 20 Years
Valuation servicing rights in tranches [Line Items]
Servicing asset at amortized value	$ 2,652,000		$ 2,652,000		2,927,000
Servicing asset, agreement term			20 years
Valuation allowance			$ 9,000		$ 33,000