Acquisition - Additional Information (Detail) (USD $)				6 Months Ended
	Jun. 30, 2014	Apr. 03, 2014	Dec. 31, 2013	Jun. 30, 2014 SCB Bancorp [Member]	Apr. 03, 2014 SCB Bancorp [Member]
Loans At Acquisition Date [Line Items]
Date of acquisition agreement				Apr. 03, 2014
Exchange ratio per share to Heartland shareholder					$ 0.4904
Share of common stock outstanding per share					$ 5.15
Common stock outstanding	9,201,786		8,630,966		1,164,442
Common stock issued				570,820
Market closing price per share					$ 22.23
Transaction value is estimated					$ 18,900,000
Costs related to the acquisition				1,200,000
Net tangible assets acquired					19,900,000
Net intangible assets acquired		822,000			822,000
Acquisition of goodwill	28,034,000	8,286,000	19,748,000		8,300,000
Purchase price of the business assets		2,548,000			4,400,000
Core deposit intangible amortization period				7 years
Loan portfolio acquired					130,500,000
Discount on loan portfolio acquired					6,400,000
Performing portion of the loan portfolio acquired					106,200,000
Estimated fair value of performing portion of the loan portfolio					$ 104,600,000