Securities (Details 1) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Securities with unrealized losses aggregated by investment category and length of time
Fair Value, Less than 12 Months	$ 47,229,000	$ 33,555,000
Unrealized Loss, Less than 12 Months	(690,000)	(388,000)
Fair Value, 12 Months or More	0	0
Unrealized Loss, 12 Months or More	0	0
Fair Value	47,229,000	33,555,000
Unrealized Loss	(690,000)	(388,000)
U.S. Government agency debt obligations [Member]
Securities with unrealized losses aggregated by investment category and length of time
Fair Value, Less than 12 Months	47,229,000	33,555,000
Unrealized Loss, Less than 12 Months	(690,000)	(388,000)
Fair Value, 12 Months or More	0	0
Unrealized Loss, 12 Months or More	0	0
Fair Value	47,229,000	33,555,000
Unrealized Loss	(690,000)	(388,000)
Mortgage-backed securities [Member]
Securities with unrealized losses aggregated by investment category and length of time
Fair Value, Less than 12 Months	0	0
Unrealized Loss, Less than 12 Months	0	0
Fair Value, 12 Months or More	0	0
Unrealized Loss, 12 Months or More	0	0
Fair Value	0	0
Unrealized Loss	0	0
Michigan Strategic Fund bonds [Member]
Securities with unrealized losses aggregated by investment category and length of time
Fair Value, Less than 12 Months	0	0
Unrealized Loss, Less than 12 Months	0	0
Fair Value, 12 Months or More	0	0
Unrealized Loss, 12 Months or More	0	0
Fair Value	0	0
Unrealized Loss	0	0
Municipal general obligation bonds [Member]
Securities with unrealized losses aggregated by investment category and length of time
Fair Value, Less than 12 Months	0	0
Unrealized Loss, Less than 12 Months	0	0
Fair Value, 12 Months or More	0	0
Unrealized Loss, 12 Months or More	0	0
Fair Value	0	0
Unrealized Loss	0	0
Municipal revenue bonds [Member]
Securities with unrealized losses aggregated by investment category and length of time
Fair Value, Less than 12 Months	0	0
Unrealized Loss, Less than 12 Months	0	0
Fair Value, 12 Months or More	0	0
Unrealized Loss, 12 Months or More	0	0
Fair Value	0	0
Unrealized Loss	0	0
Mutual funds [Member]
Securities with unrealized losses aggregated by investment category and length of time
Fair Value, Less than 12 Months	0	0
Unrealized Loss, Less than 12 Months	0	0
Fair Value, 12 Months or More	0	0
Unrealized Loss, 12 Months or More	0	0
Fair Value	0	0
Unrealized Loss	$ 0	$ 0