Condensed Parent Company Only Financial Statements (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended												12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	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, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities:
Net income	$ 1,805	$ 1,782	$ 1,403	$ 1,450	$ 1,561	$ 13	$ 1,561	$ 1,609	$ 1,685	$ 1,226	$ 1,918	$ 1,180	$ 6,440	$ 4,744	$ 6,009
Adjustments to reconcile net income to net cash provided by operating activities:
Other assets													80	1,590	386
Net cash provided by operating activities													9,035	13,034	7,556
Cash flows from investing activities:
Net cash provided by (used in) investing activities													10,016	(25,570)	20,283
Cash flows from financing activities:
Repayment of senior subordinated notes													0	(3,000)	0
Proceeds from exercise of stock options															9
Dividends declared													(1,316)	(1,289)	(1,247)
Net cash used in financing activities													(25,467)	(4,789)	(17,197)
Net increase (decrease) in cash and due from banks													(6,416)	(17,325)	10,642
Cash and cash equivalents at beginning				31,522	17,080			48,847				38,205	31,522	48,847	38,205
Cash and cash equivalents at end	25,106				31,522	17,080			48,847				25,106	31,522	48,847
Parent Company [Member]
Cash flows from operating activities:
Net income													6,440	4,744	6,009
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed net income of Peoples State Bank													(2,931)	(1,202)	801
Other assets													41	147	(21)
Decrease in other liabilities													(5)	(98)	(2)
Increase (decrease) in dividends payable													8	644	(583)
Net cash provided by operating activities													3,553	4,235	6,204
Cash flows from investing activities:
Purchase Marathon State Bank common stock													0	0	(5,482)
Investment in Peoples State Bank													0	0	(5)
Net cash provided by (used in) investing activities													0	0	(5,487)
Cash flows from financing activities:
Repayment of senior subordinated notes													0	(3,000)	0
Proceeds from other borrowings													0	2,000	0
Repayment of other borrowings													(1,000)	(500)	0
Proceeds from exercise of stock options													0	0	9
Dividends declared													(1,316)	(1,289)	(1,247)
Purchase of treasury stock													(913)	(269)	(262)
Net cash used in financing activities													(3,229)	(3,058)	(1,500)
Net increase (decrease) in cash and due from banks													324	1,177	(783)
Cash and cash equivalents at beginning				3,502				2,325				3,108	3,502	2,325	3,108
Cash and cash equivalents at end	$ 3,826				$ 3,502				$ 2,325				$ 3,826	$ 3,502	$ 2,325