Condensed Financial Information (Parent Company Only) (Condensed Statements of Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Net income	$ 18,864	$ 12,315	$ 13,241
Other Comprehensive Income (Loss)
Less: Reclassification adjustment for realized gains included in net included in net income	(804)	(708)	(1,023)
Net unrealized gain (loss) on derivative used for cash flow hedges			1
Net unrealized gain (loss) relating to defined benefit plan	(109)	(20)	62
Other Comprehensive Income (Loss), before Tax	(3,825)	2,384	(4,218)
Income tax (benefit) expense related to other comprehensive income	820	(749)	1,474
Other comprehensive income (loss)	(3,005)	1,635	(2,744)
Comprehensive income	15,859	13,950	10,497
MutualFirst Financial, Inc.
Condensed Financial Statements, Captions [Line Items]
Net income	18,864	12,315	13,241
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	(2,912)	3,112	(3,258)
Less: Reclassification adjustment for realized gains included in net included in net income	(804)	(708)	(1,023)
Net unrealized gain (loss) on derivative used for cash flow hedges			1
Net unrealized gain (loss) relating to defined benefit plan	(109)	(20)	62
Other Comprehensive Income (Loss), before Tax	(3,825)	2,384	(4,218)
Income tax (benefit) expense related to other comprehensive income	820	(749)	1,474
Other comprehensive income (loss)	(3,005)	1,635	(2,744)
Comprehensive income	$ 15,859	$ 13,950	$ 10,497