Summary of Quarterly Financial Information (Unaudited) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information Disclosure [Abstract]
Net interest income	$ 46,357	$ 39,880	$ 38,924	$ 38,667	$ 37,974	$ 36,812	$ 37,177	$ 38,193	$ 163,828	$ 150,156	$ 145,394
Provision for loan and lease losses	2,049	5,149	1,862	637	3,350	(502)	3,000	2,354	9,697	8,202	29,365
NET INTEREST INCOME AFTER PROVISION FOR LOAN AND LEASE LOSSES	44,308	34,731	37,062	38,030	34,624	37,314	34,177	35,839	154,131	141,954	116,029
Noninterest income	17,574	20,718	24,858	26,468	27,230	29,766	28,278	23,388	89,618	108,662	59,577
Noninterest expense	53,901	47,147	48,766	46,747	54,623	47,159	41,459	40,140	196,561	183,381	137,296
Income taxes (includes $1,884 of income tax expense reclassified from accumulated other comprehensive income for the year ended December 31, 2013)	46	1,492	3,598	5,199	(2,258)	6,338	7,032	6,272	10,335	17,384	10,302
NET INCOME	7,935	6,810	9,556	12,552	9,489	13,583	13,964	12,815	36,853	49,851	28,008
Net income available to noncontrolling interest, net of tax	0	0	0	(64)	(82)	4	(7)	26	(64)	(59)	36
NET INCOME ATTRIBUTABLE TO HEARTLAND	7,935	6,810	9,556	12,488	9,407	13,587	13,957	12,841	36,789	49,792	28,044
Preferred stock dividends and discount	(204)	(276)	(205)	(408)	(409)	(949)	(1,021)	(1,021)	(1,093)	(3,400)	(7,640)
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS	$ 7,731	$ 6,534	$ 9,351	$ 12,080	$ 8,998	$ 12,638	$ 12,936	$ 11,820	$ 35,696	$ 46,392	$ 20,404
Earnings per common share — basic (in dollars per share)	$ 0.43	$ 0.39	$ 0.55	$ 0.72	$ 0.54	$ 0.77	$ 0.79	$ 0.72	$ 2.08	$ 2.81	$ 1.24
Earnings per common share — diluted (in dollars per share)	$ 0.42	$ 0.38	$ 0.54	$ 0.70	$ 0.54	$ 0.75	$ 0.77	$ 0.71	$ 2.04	$ 2.77	$ 1.23
Cash dividends per share common stock (in dollars per share)	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.20	$ 0.10	$ 0.10	$ 0.10	$ 0.40	$ 0.50	$ 0.40
Book value per common share	$ 19.44	$ 18.58	$ 18.51	$ 19.54	$ 19.02	$ 18.81	$ 17.65	$ 17.09
Weighted average common shares outstanding	18,096,345	16,935,581	16,907,405	16,851,672	16,534,217	16,473,760	16,474,455	16,490,051	17,199,000	16,518,000	16,437,000
Weighted average diluted common shares outstanding	18,360,470	17,221,154	17,203,924	17,187,180	16,812,947	16,745,968	16,717,846	16,729,925	17,460,000	16,769,000	16,576,000