Summary of Significant Accounting Policies (Earnings per Share) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Net income attributable to Heartland	$ 12,263	$ 11,973	$ 10,774	$ 6,890	$ 7,935	$ 6,810	$ 9,556	$ 12,488	$ 41,900	$ 36,789	$ 49,792
Preferred dividends and discount	(204)	(205)	(204)	(204)	(204)	(276)	(205)	(408)	(817)	(1,093)	(3,400)
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS	$ 12,059	$ 11,768	$ 10,570	$ 6,686	$ 7,731	$ 6,534	$ 9,351	$ 12,080	$ 41,083	$ 35,696	$ 46,392
Weighted average common shares outstanding for basic earnings per share	18,482,059	18,468,762	18,458,113	18,437,253	18,096,345	16,935,581	16,907,405	16,851,672	18,462,000	17,199,000	16,518,000
Assumed incremental common shares issued upon exercise of stock options and non-vested restricted stock units									280,000	261,000	251,000
Weighted average common shares for diluted earnings per share	18,762,272	18,752,748	18,746,735	18,724,936	18,360,470	17,221,154	17,203,924	17,187,180	18,742,000	17,460,000	16,769,000
Earnings per common share — basic (in dollars per share)	$ 0.65	$ 0.64	$ 0.57	$ 0.36	$ 0.43	$ 0.39	$ 0.55	$ 0.72	$ 2.23	$ 2.08	$ 2.81
Earnings per common share — diluted (in dollars per share)	$ 0.64	$ 0.63	$ 0.56	$ 0.36	$ 0.42	$ 0.38	$ 0.54	$ 0.70	$ 2.19	$ 2.04	$ 2.77
Number of antidilutive stock options excluded from diluted earnings per share computation (in shares)									88,000	99,000	106,000