Basis of Presentation (Policies)	9 Months Ended
Basis of Presentation (Policies)	Sep. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	BASIS OF PRESENTATION The interim unaudited consolidated financial statements contained herein should be read in conjunction with the audited consolidated financial statements and accompanying notes to the consolidated financial statements for the fiscal year ended December 31, 2015, included in the Form 10-K of Heartland Financial USA, Inc. ("Heartland") filed with the Securities and Exchange Commission ("SEC") on March 11, 2016. Accordingly, footnote disclosures which would substantially duplicate the disclosure contained in the audited consolidated financial statements have been omitted. The financial information of Heartland included herein has been prepared in accordance with U.S. generally accepted accounting principles for interim financial reporting and has been prepared pursuant to the rules and regulations for reporting on Form 10-Q and Rule 10-01 of Regulation S-X. Such information reflects all adjustments (consisting of normal recurring adjustments), that are, in the opinion of management, necessary for a fair presentation of the financial position and results of operations for the periods presented. The results of the interim period ended September 30, 2016, are not necessarily indicative of the results expected for the year ending December 31, 2016.
Earnings Per Share	Earnings Per Share Basic earnings per share is determined using net income available to common stockholders and weighted average common shares outstanding. Diluted earnings per share is computed by dividing net income available to common stockholders by the weighted average common shares and assumed incremental common shares issued.
Stock-Based Compensation	Stock-Based Compensation Heartland may grant, through its Nominating and Compensation Committee (the "Compensation Committee"), non-qualified and incentive stock options, stock appreciation rights, stock awards, restricted stock, restricted stock units and cash incentive awards, under its 2012 Long-Term Incentive Plan (the "Plan"). The Plan was originally approved by stockholders in May 2012 and was amended effective March 8, 2016, to increase the number of shares of common stock authorized for issuance and make certain other changes to the Plan. As of September 30, 2016, 549,144 shares of common stock were available for issuance under future awards that may be granted under the Plan to employees and directors of, and service providers to, Heartland or its subsidiaries. Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") Topic 718, "Compensation-Stock Compensation" requires the measurement of the cost of employee services received in exchange for an award of equity instruments based upon the fair value of the award on the grant date. The cost of the award is based upon its fair value estimated on the date of grant and recognized in the consolidated statements of income over the vesting period of the award. The fair market value of restricted stock and restricted stock units is based on the fair value of the underlying shares of common stock on the date of grant. The fair value of stock options is estimated on the date of grant using the Black-Scholes model.
Effect of New Financial Accounting Standards	Effect of New Financial Accounting Standards In May 2014, the FASB issued ASU 2014-09, "Revenue from Contracts with Customers." The amendment clarifies the principles for recognizing revenue and develops a common revenue standard. The amendment outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. The core principle of the revenue model is that “an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services.” In applying the revenue model to contracts within its scope, an entity should apply the following steps: (i) identify the contract(s) with a customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations in the contract, and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The amendment applies to all contracts with customers except those that are within the scope of other topics in the FASB Codification. The standard also requires significantly expanded disclosures about revenue recognition. The amendment is effective for annual reporting periods beginning after December 15, 2017 (including interim reporting periods within those periods). Early application is not permitted. Heartland intends to adopt the accounting standard during the first quarter of 2018, as required, and is currently evaluating the impact on its results of operations, financial position, and liquidity. In November 2014, the FASB issued ASU 2014-16, "Derivatives and Hedging (Topic 815): Determining Whether a Host Contract in a Hybrid Financial Instrument Issued in the Form of a Share is More Akin to Debt or to Equity." The amendment clarifies how current guidance should be interpreted in evaluating the characteristics and risks of a host contract in a hybrid financial instrument issued in the form of a share. One criterion requires evaluating whether the nature of the host contract is more akin to debt or to equity and whether the economic characteristics and risks of the embedded derivative feature are "clearly and closely related" to the host contract. In making that evaluation, an issuer or investor must consider all terms and features in a hybrid financial instrument including the embedded derivative feature that is being evaluated for separate accounting or may consider all terms and features in the hybrid financial instrument except for the embedded derivative feature that is being evaluated for separate accounting. This ASU is effective for annual periods and interim periods within those annual periods beginning after December 15, 2015, with early adoption permitted. Heartland adopted this standard on January 1, 2016, and the adoption of this standard did not have a material impact on its results of operations, financial position, and liquidity. In January 2015, the FASB issued ASU 2015-01, "Income Statement-Extraordinary and Unusual Items." The amendment eliminates from U.S. GAAP the concept of extraordinary items. Presently, an event or transaction is presumed to be an ordinary and usual activity of the reporting entity unless evidence clearly supports its classification as an extraordinary item. If an event or transaction meets the criteria for extraordinary classification, an entity is required to segregate the extraordinary item from the results of ordinary operations and show the item separately in the income statement, net of tax, after income from continuing operations. This amended guidance will prohibit separate disclosure of extraordinary items in the income statement. This amendment is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. Entities may apply the amendment prospectively or retrospectively to all prior periods presented in the financial statements. Early adoption is permitted provided that the guidance is applied from the beginning of the fiscal year of adoption. Heartland adopted this standard on January 1, 2016, and the adoption of this standard did not have a material impact on the results of operations, financial position, and liquidity. In April 2015, the FASB issued ASU 2015-05, "Intangibles-Goodwill and Other-Internal-Use Software." The amendment intends to provide guidance to customers about whether a cloud computing arrangement includes a software license. If a cloud computing arrangement includes a software license, then the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. The guidance will not change GAAP for a customer's accounting for service contracts. As a result, all software licenses within the scope of this guidance will be accounted for consistently with other licenses of intangible assets. This amendment is effective for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years. Entities can elect to adopt the standard either retrospectively or prospectively to all cloud computing arrangements entered into or materially modified after the adoption date. Early adoption is permitted. Heartland adopted this standard on January 1, 2016, and the adoption did not have a material impact on the results of operations, financial position, and liquidity. In September 2015, the FASB issued ASU 2015-16, "Simplifying the Accounting for Measurement-Period Adjustments." The amendment eliminates the requirement of Topic 805, Business Combinations, to retrospectively adjust the financial statements for measurement-period adjustments that occur in periods after a business combination is consummated. Measurement-period adjustments are calculated as if they were known at the acquisition date, but are recognized in the reporting period in which they are determined. Prior period information is not revised. Additional disclosures are required about the impact on current period income statement line items of adjustments that would have been recognized in prior periods if prior period information had been revised. This amendment is effective for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years. Early adoption is permitted if financial statements have not been issued. Heartland adopted this standard effective September 30, 2015. The adoption of this standard did not have a material impact on the results of operations, financial position, and liquidity. In January 2016, the FASB issued guidance ASU 2016-01, "Recognition and Measurement of Financial Assets and Financial Liabilities." The amendments in ASU 2016-01 to Subtopic 825-10, Financial Instruments, contain the following elements: (1) requires equity investments to be measured at fair value with changes in fair value recognized in net income; (2) simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment; (3) eliminates the requirement for public entities to disclose the methods and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet; (4) requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes; (5) requires an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments; (6) requires separate presentation of financial assets and financial liabilities by measurement category and form of financial asset on the balance sheet or accompanying notes to the financial statements; (7) clarifies that the entity should evaluate the need for a valuation allowance on a deferred tax asset related to available for sale securities in combination with the entity's other deferred tax assets. The amendments are effective for fiscal years beginning after December 15, 2017, and for interim periods within those fiscal years. Except for the early application of the amendment noted in item (5) above, early adoption of the amendments in this update is not permitted. Heartland intends to adopt the accounting standard in 2018, as required, and is currently evaluating the potential impact of this guidance on its results of operations, financial position, and liquidity. In February 2016, the FASB issued ASU 2016-02, "Leases (Topic 842)." Topic 842 requires a lessee to recognize a lease liability and a right of use asset for each lease, with the exception of short term leases, at the commencement date of the lease and disclose key information about the leasing arrangement. Accounting requirements applied by lessors is largely unchanged. The amendment is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, and will be applied on a modified retrospective basis. Heartland intends to adopt the accounting standard in 2019, as required, and is currently evaluating the potential impact of this guidance on its results of operations, financial position, and liquidity. In March 2016, the FASB issued ASU 2016-09, "Compensation-Stock Compensation (Topic 718)." The amendments in this ASU simplify several aspects of the accounting for share-based payments, including income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. The amendments in this ASU are effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods. Early adoption is permitted for any interim or annual period prior to the effective date. An entity that elects early adoption must adopt all of the amendments in the same period. Heartland intends to adopt this ASU in 2017, as required, and is currently evaluating the potential impact of this guidance on its results of operations, financial position, and liquidity. In June 2016, the FASB issued ASU 2016-13, "Financial Instruments - Credit Losses (Topic 326)." The amendments in this ASU require a financial asset (or a group of financial assets) measured at amortized cost basis to be presented at the net amount expected to be collected. The allowance for credit losses is a valuation account that is deducted from the amortized cost basis of the financial asset(s) to present the net carrying value at the amount expected to be collected on the financial asset. The amendments in this ASU indicate that an entity should not use the length of time a security has been in an unrealized loss position to avoid recording a credit loss. In addition, in determining whether a credit loss exists, the amendments in this ASU also remove the requirements to consider the historical and implied volatility of the fair value of a security and recoveries or declines in fair value after the balance sheet date. The amendment is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. An entity may adopt the amendments earlier as of the fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Heartland intends to adopt the accounting standard in 2020, as required, and is currently evaluating the potential impact of this guidance on its results of operations, financial position, and liquidity. In August 2016, the FASB issued ASU 2016-15, "Statement of Cash Flows (Topic 230) - Classification of Certain Cash Receipts and Cash Payments." The amendments in this update address eight specific cash flow issues with the objective of reducing the existing diversity in practice. The amendment is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. If an entity early adopts the amendments in an interim period, any adjustments should be reflected as of the beginning of the fiscal year that includes the interim period. An entity that elects early adoption must adopt all of the amendments in the same period. The amendments in this update should be applied using a retrospective transition method to each period presented. Heartland intends to adopt this ASU in 2018, as required, and is currently evaluating the potential impact on its results of operations, financial position, and liquidity.
Fair Value Hierarchy	Fair Value Hierarchy Under ASC 820, assets and liabilities are grouped at fair value in three levels, based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. These levels are: Level 1 — Valuation is based upon quoted prices for identical instruments in active markets. Level 2 — Valuation is based upon quoted prices for similar instruments in active markets, or similar instruments in markets that are not active, and model-based valuation techniques for all significant assumptions are observable in the market. Level 3 — Valuation is generated from model-based techniques that use at least one significant assumption not observable in the market. These unobservable assumptions reflect estimates of assumptions that market participants would use in pricing the asset or liability. Valuation techniques include use of option pricing models, discounted cash flow models and similar techniques. The following is a description of valuation methodologies used for assets and liabilities recorded at fair value on a recurring or non-recurring basis. Assets Securities Available for Sale and Held to Maturity Securities available for sale are recorded at fair value on a recurring basis. Securities held to maturity are generally recorded at cost and are recorded at fair value only to the extent a decline in fair value is determined to be other-than-temporary. Fair value measurement is based upon quoted prices, if available. If quoted prices are not available, fair values are measured using independent pricing models or other model-based valuation techniques such as the present value of future cash flows, adjusted for the security's credit rating, prepayment assumptions and other factors such as credit loss assumptions. Level 1 securities include those traded on an active exchange, such as the New York Stock Exchange, as well as U.S. Treasury securities. Level 2 securities include U.S. government and agency securities, mortgage-backed securities and private collateralized mortgage obligations, municipal bonds and corporate debt securities. Level 3 securities consist primarily of Z-TRANCHE mortgage-backed securities and corporate debt securities. On a quarterly basis, a secondary independent pricing service is used for a sample of securities to validate the pricing from Heartland's primary pricing service. Loans Held for Sale Loans held for sale are carried at the lower of cost or fair value on an aggregate basis. The fair value of loans held for sale is based on what secondary markets are currently offering for portfolios with similar characteristics. As such, Heartland classifies loans held for sale subjected to nonrecurring fair value adjustments as Level 2. Loans Held to Maturity Heartland does not record loans held to maturity at fair value on a recurring basis. However, from time to time, a loan is considered impaired and an allowance for loan losses is established. Loans for which it is probable that payment of interest and principal will not be made in accordance with the contractual terms of the loan agreement are considered impaired. Once a loan is identified as individually impaired, management measures impairment in accordance with ASC 310. The fair value of impaired loans is measured using one of the following impairment methods: 1) the present value of expected future cash flows discounted at the loan's effective interest rate or 2) the observable market price of the loan or 3) the fair value of the collateral if the loan is collateral dependent. In accordance with ASC 820, impaired loans measured at fair value are classified as nonrecurring Level 3 in the fair value hierarchy. Premises, Furniture and Equipment Held for Sale Heartland values premises, furniture and equipment held for sale based on third-party appraisals less estimated disposal costs. Heartland considers third party appraisals, as well as independent fair value assessments from Realtors or persons involved in selling bank premises, furniture and equipment, in determining the fair value of particular properties. Accordingly, the valuation of premises, furniture and equipment held for sale is subject to significant external and internal judgment. Heartland periodically reviews premises, furniture and equipment held for sale to determine if the fair value of the property, less disposal costs, has declined below its recorded book value and records any adjustments accordingly. Premises, furniture and equipment held for sale are classified as nonrecurring Level 3 in the fair value hierarchy. Mortgage Servicing Rights Mortgage servicing rights assets represent the value associated with servicing residential real estate loans that have been sold to outside investors with servicing retained. Heartland uses the amortization method (i.e., the lower of amortized cost or estimated fair value measured on a nonrecurring basis), not fair value measurement accounting, to determine the carrying value of its mortgage servicing rights. The fair value for servicing assets is determined through discounted cash flow analysis and utilizes discount rates, prepayment speeds and delinquency rate assumptions as inputs. All of these assumptions require a significant degree of management estimation and judgment. Mortgage servicing rights are subject to impairment testing. The carrying values of these rights are reviewed quarterly for impairment based upon the calculation of fair value as performed by an outside third party. For purposes of measuring impairment, the rights are stratified into certain risk characteristics including note type and note term. If the valuation model reflects a fair value less than the carrying value, mortgage servicing rights are adjusted to fair value through a valuation allowance. Heartland classifies mortgage servicing rights as nonrecurring with Level 3 measurement inputs. Commercial Servicing Rights Commercial servicing rights assets represent the value associated with servicing commercial loans guaranteed by the Small Business Administration and the United States Department of Agriculture that have been sold with servicing retained by Heartland. Heartland uses the amortization method (i.e., the lower of amortized cost or estimated fair value measured on a nonrecurring basis), not fair value measurement accounting, to determine the carrying value of its commercial servicing rights. The fair value for servicing assets is determined through market prices for comparable servicing contracts, when available, or through a valuation model that calculates the present value of estimated future net servicing income. Inputs utilized include discount rates, prepayment speeds and delinquency rate assumptions as inputs. All of these assumptions require a significant degree of management estimation and judgment. Commercial servicing rights are subject to impairment testing, and the carrying values of these rights are reviewed quarterly for impairment based upon the calculation of fair value as performed by an outside third party. If the valuation model reflects a fair value less than the carrying value, commercial servicing rights are adjusted to fair value through a valuation allowance. Heartland classifies commercial servicing rights as nonrecurring with Level 3 measurement inputs. Derivative Financial Instruments Heartland's current interest rate risk strategy includes interest rate swaps. The valuation of these instruments is determined using widely accepted valuation techniques including discounted cash flow analysis on the expected cash flows of each derivative. This analysis reflects the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs, including interest rate curves and implied volatilities. To comply with the provisions of ASC 820, Heartland incorporates credit valuation adjustments to appropriately reflect both its own nonperformance risk and the respective counterparty's nonperformance risk in the fair value measurements. In adjusting the fair value of its derivative contracts for the effect of nonperformance risk, Heartland has considered the impact of netting any applicable credit enhancements, such as collateral postings, thresholds, mutual puts, and guarantees. Although Heartland has determined that the majority of the inputs used to value its derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with its derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by itself and its counterparties. However, as of September 30, 2016, and December 31, 2015, Heartland has assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions and has determined that the credit valuation adjustments are not significant to the overall valuation of its derivatives. As a result, Heartland has determined that its derivative valuations in their entirety are classified in Level 2 of the fair value hierarchy. Interest rate lock commitments Heartland uses an internal valuation model that relies on internally developed inputs to estimate the fair value of its interest rate lock commitments which is based on unobservable inputs that reflect management's assumptions and specific information about each borrower. Interest rate lock commitments are classified in Level 3 of the fair value hierarchy. Forward commitments The fair value of forward commitments are estimated using an internal valuation model, which includes current trade pricing for similar financial instruments in active markets that Heartland has the ability to access and are classified in Level 2 of the fair value hierarchy. Other Real Estate Owned Other real estate owned ("OREO") represents property acquired through foreclosures and settlements of loans. Property acquired is carried at the fair value of the property at the time of acquisition (representing the property's cost basis), plus any acquisition costs, or the estimated fair value of the property, less disposal costs. Heartland considers third party appraisals, as well as independent fair value assessments from realtors or persons involved in selling OREO, in determining the fair value of particular properties. Accordingly, the valuation of OREO is subject to significant external and internal judgment. Heartland periodically reviews OREO to determine if the fair value of the property, less disposal costs, has declined below its recorded book value and records any adjustments accordingly. OREO is classified as nonrecurring Level 3 of the fair value hierarchy.