Condensed Financial Information (Parent Company Only) (Condensed Statements of Cash Flows) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Activities
Net income	$ 12,315	$ 13,241	$ 12,262
Item not requiring cash
Deferred income tax	3,562	1,537	1,926
Other	259	143	143
Net cash provided by operating activities	20,042	18,551	15,933
Investing Activities
Net cash used in investing activities	(41,079)	(76,606)	(67,532)
Financing Activities
Cash dividends	(4,862)	(4,284)	(3,550)
Proceeds from stock options exercised	1,156	976	2,011
Net cash provided by financing activities	21,518	64,000	42,939
Net Change in Cash and Cash Equivalents	481	5,945	(8,660)
Cash and Cash Equivalents, Beginning of Period	26,860	20,915	29,575
Cash and Cash Equivalents, End of Period	27,341	26,860	20,915
MutualFirst Financial, Inc.
Operating Activities
Net income	12,315	13,241	12,262
Item not requiring cash
Deferred income tax	(14)	200	(102)
(Equity in undistributed income) distributions in excess of income of subsidiary	2,239	(1,818)	(9,252)
Other	74	(183)	13
Net cash provided by operating activities	14,614	11,440	2,921
Investing Activities
Investment in subsidiary		(100)	(250)
Net cash used in investing activities		(100)	(250)
Financing Activities
Repayments of other borrowings		(5,312)	(759)
Stock repurchased		(4,354)
Cash dividends	(4,862)	(4,284)	(3,550)
Proceeds from stock options exercised	1,156	976	2,011
Net cash provided by financing activities	(3,706)	(12,974)	(2,298)
Net Change in Cash and Cash Equivalents	10,908	(1,634)	373
Cash and Cash Equivalents, Beginning of Period	1,122	2,756	2,383
Cash and Cash Equivalents, End of Period	$ 12,030	$ 1,122	$ 2,756