Summary of Quarterly Financial Information (Unaudited) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	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	Dec. 31, 2011	Dec. 31, 2010
Quarterly Financial Information Disclosure [Abstract]
Net Interest Income	$ 37,974	$ 36,812	$ 37,177	$ 38,193	$ 36,837	$ 36,235	$ 36,601	$ 35,721	$ 150,156	$ 145,394	$ 143,052
Provision for loan and lease losses	3,350	(502)	3,000	2,354	7,784	7,727	3,845	10,009	8,202	29,365	32,508
NET INTEREST INCOME AFTER PROVISION FOR LOAN AND LEASE LOSSES	34,624	37,314	34,177	35,839	29,053	28,508	32,756	25,712	141,954	116,029	110,544
Noninterest income	27,230	29,766	28,278	23,388	19,038	13,262	14,669	12,608	108,662	59,577	52,329
Noninterest expense	54,623	47,159	41,459	40,140	40,203	31,863	32,343	32,887	183,381	137,296	129,239
Income taxes	(2,258)	6,338	7,032	6,272	1,671	2,549	4,870	1,212	17,384	10,302	9,846
NET INCOME	9,489	13,583	13,964	12,815	6,217	7,358	10,212	4,221	49,851	28,008	23,788
Net income (loss) available to noncontrolling interest, net of tax	(82)	4	(7)	26	31	(20)	9	16	(59)	36	115
NET INCOME ATTRIBUTABLE TO HEARTLAND	9,407	13,587	13,957	12,841	6,248	7,338	10,221	4,237	49,792	28,044	23,903
Preferred stock dividends and discount	(409)	(949)	(1,021)	(1,021)	(1,021)	(3,947)	(1,336)	(1,336)	(3,400)	(7,640)	(5,344)
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS	$ 8,998	$ 12,638	$ 12,936	$ 11,820	$ 5,227	$ 3,391	$ 8,885	$ 2,901	$ 46,392	$ 20,404	$ 18,559
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
Cash dividends per share common stock (in dollars per share)	$ 0.20	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.50	$ 0.40	$ 0.40
Book value per common share	$ 19.02	$ 18.81	$ 17.65	$ 17.09	$ 16.29	$ 16.33	$ 16.04	$ 15.28
Weighted average common shares outstanding (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
Weighted average diluted common shares outstanding	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