Summary of Significant Accounting Policies (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012 segment	Dec. 31, 2011	Dec. 31, 2010
Goodwill and Intangible Assets:
Mortgage servicing rights, valuation allowance									$ 496,000	$ 19,000
Segment Reporting:
Number of reportable segment									2
Mortgage Servicing and Transfers of Financial Assets:
Aggregate unpaid principal balance	2,200,000,000				1,540,000,000				2,200,000,000	1,540,000,000
Earnings Per Share:
Net income attributable to Heartland	9,407,000	13,587,000	13,957,000	12,841,000	6,248,000	7,338,000	10,221,000	4,237,000	49,792,000	28,044,000	23,903,000
Preferred dividends and discount	(409,000)	(949,000)	(1,021,000)	(1,021,000)	(1,021,000)	(3,947,000)	(1,336,000)	(1,336,000)	(3,400,000)	(7,640,000)	(5,344,000)
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS	$ 8,998,000	$ 12,638,000	$ 12,936,000	$ 11,820,000	$ 5,227,000	$ 3,391,000	$ 8,885,000	$ 2,901,000	$ 46,392,000	$ 20,404,000	$ 18,559,000
Weighted average common shares outstanding for basic earnings per share (in shares)	16,534,217	16,473,760	16,474,455	16,490,051	16,460,613	16,444,369	16,426,741	16,407,845	16,518,000	16,437,000	16,372,000
Assumed incremental common shares issued upon exercise of stock options (in shares)									251,000	139,000	90,000
Weighted average common shares for diluted earnings per share (in shares)	16,812,947	16,745,968	16,717,846	16,729,925	16,599,741	16,585,021	16,568,701	16,557,353	16,769,000	16,576,000	16,462,000
Earnings per common share — basic (in dollars per share)	$ 0.54	$ 0.77	$ 0.79	$ 0.72	$ 0.32	$ 0.21	$ 0.54	$ 0.18	$ 2.81	$ 1.24	$ 1.13
Earnings per common share — diluted (in dollars per share)	$ 0.54	$ 0.75	$ 0.77	$ 0.71	$ 0.31	$ 0.20	$ 0.54	$ 0.18	$ 2.77	$ 1.23	$ 1.13
Number of antidilutive stock options excluded from diluted earnings per share computation (in shares)									106,000	514,000	562,000
Building | Minimum
Premises, Furniture and Equipment:
Useful life									18 years
Building | Maximum
Premises, Furniture and Equipment:
Useful life									39 years
Land Improvements
Premises, Furniture and Equipment:
Useful life									15 years
Furniture and Equipment | Minimum
Premises, Furniture and Equipment:
Useful life									3 years
Furniture and Equipment | Maximum
Premises, Furniture and Equipment:
Useful life									7 years
Core Deposits | Minimum
Goodwill and Intangible Assets:
Useful life									8 years
Core Deposits | Maximum
Goodwill and Intangible Assets:
Useful life									18 years
Customer Relationships
Goodwill and Intangible Assets:
Useful life									22 years
Community Banking
Segment Reporting:
Number of reportable segment									1
Mortgage Banking Operations
Segment Reporting:
Number of reportable segment									1
Minnesota Bank & Trust
Basis of Presentation [Line Items]
Ownership percentage	80.00%								80.00%