Condensed Parent Company Only Financial Statements (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended												12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net income	$ 1,685	$ 1,226	$ 1,918	$ 1,180	$ 1,400	$ 1,394	$ 1,226	$ 1,285	$ 1,334	$ 1,331	$ 1,208	$ 881	$ 6,009	$ 5,305	$ 4,754
Net cash provided by operating activities													7,556	9,657	8,719
Net cash provided by investing activities													20,283	(7,782)	(2,499)
Proceeds from exercise of stock options													9	45
Dividends declared													(1,247)	(1,168)	(1,128)
Purchase of treasury stock													(262)
Net cash used in financing activities													(17,197)	(4,001)	7,774
Net (decrease)/increase in cash and cash equivalents													10,642	(2,126)	13,994
The Corporation
Net income													6,009	5,305	4,754
Equity in undistributed net income of Peoples State Bank													801	(3,057)	(2,883)
(Increase) decrease in other assets													(21)	5	(55)
(Decrease) increase in other liabilities													(2)	28	(3)
(Decrease) increase in dividends payable													(583)	20	17
Net cash provided by operating activities													6,204	2,301	1,830
Investment in Peoples State Bank													(5)
Purchase Marathon State Bank Common Stock													(5,482)
Net cash provided by investing activities													(5,487)
Proceeds from exercise of stock options													9	45
Dividends declared													(1,247)	(1,168)	(1,128)
Purchase of treasury stock													(262)
Net cash used in financing activities													(1,500)	(1,123)	(1,128)
Net (decrease)/increase in cash and cash equivalents													(783)	1,178	702
Cash and cash equivalents at beginning of year				3,108				1,930				1,228	3,108	1,930	1,228
Cash and cash equivalents at end of year	$ 2,325				$ 3,108				$ 1,930				$ 2,325	$ 3,108	$ 1,930