Basis of Presentation (Earnings per share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share
Net income attributable to Heartland	$ 20,208	$ 14,582	$ 61,187	$ 45,451
Preferred dividends	(53)	(205)	(273)	(613)
Interest expense on convertible preferred debt	17	0	48	0
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS	$ 20,172	$ 14,377	$ 60,962	$ 44,838
Weighted average common shares outstanding for basic earnings per share (in shares)	24,601	20,620	24,262	20,483
Assumed incremental common shares issued upon exercise of stock options and non-vested restricted stock units (in shares)	322	273	319	269
Weighted average common shares for diluted earnings per share (shares)	24,923	20,893	24,581	20,752
Earnings per common share — basic (in dollars per share)	$ 0.82	$ 0.70	$ 2.51	$ 2.19
Earnings per common share — diluted (in dollars per share)	$ 0.81	$ 0.69	$ 2.48	$ 2.16
Number of antidilutive common stock equivalents excluded from diluted earnings per share computation (in shares)	0	0	0	0