Cover - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 24, 2021	Jun. 30, 2020
Entity Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Entity File Number	001-15393
Entity Registrant Name	HEARTLAND FINANCIAL USA, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	42-1405748
Entity Address, Address Line One	1398 Central Avenue,
Entity Address, City or Town	Dubuque
Entity Address, State or Province	IA
Entity Address, Postal Zip Code	52001
City Area Code	(563)
Local Phone Number	589-2100
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 1,161,388,720
Entity Common Stock, Shares Outstanding		42,096,266
Documents Incorporated by Reference	Portions of the Proxy Statement for the 2021 Annual Meeting of Stockholders, which will be filed no later than 120 days after December 31, 2020, are incorporated by reference into Part III.
Entity Central Index Key	0000920112
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Common Stock $1.00 par value
Entity Information [Line Items]
Title of 12(b) Security	Common Stock $1.00 par value
Trading Symbol	HTLF
Security Exchange Name	NASDAQ
Depositary Shares, each representing 1/400th interest in a share of 7.00% Fixed-Rate Reset Non-Cumulative Perpetual Preferred Stock, Series E
Entity Information [Line Items]
Title of 12(b) Security	Depositary Shares, each representing 1/400th interest in a share of 7.00% Fixed-Rate Reset Non-Cumulative Perpetual Preferred Stock, Series E
Trading Symbol	HTLFP
Security Exchange Name	NASDAQ