Condensed Financial Information (Parent Company Only) (Condensed Statements of Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Net Income	$ 23,751	$ 18,864	$ 12,315
Other Comprehensive Income (Loss)
Less: Reclassification adjustment for realized gains included in net included in net income	(1,014)	(804)	(708)
Net unrealized loss related to defined benefit plan	(215)	(109)	(20)
Other Comprehensive Income (Loss), before Tax	13,649	(3,825)	2,384
Income tax benefit (expense) related to other comprehensive income	(2,875)	820	(749)
Other comprehensive income (loss)	10,774	(3,005)	1,635
Comprehensive income	34,525	15,859	13,950
MutualFirst Financial, Inc.
Condensed Financial Statements, Captions [Line Items]
Net Income	23,751	18,864	12,315
Other Comprehensive Income (Loss)
Net unrealized gain on securities available for sale for which a portion of an other-than-temporary impairment has been recognized in income	14,878	(2,912)	3,112
Less: Reclassification adjustment for realized gains included in net included in net income	(1,014)	(804)	(708)
Net unrealized loss related to defined benefit plan	(215)	(109)	(20)
Other Comprehensive Income (Loss), before Tax	13,649	(3,825)	2,384
Income tax benefit (expense) related to other comprehensive income	(2,875)	820	(749)
Other comprehensive income (loss)	10,774	(3,005)	1,635
Comprehensive income	$ 34,525	$ 15,859	$ 13,950