Note 3 - Securities (Details) (USD $)												6 Months Ended
	Jun. 30, 2014		Dec. 31, 2013		Jun. 30, 2014 Debt Securities [Member]	Jun. 30, 2014 Mutual Funds [Member]	Dec. 31, 2013 Mutual Funds [Member]	Jun. 30, 2014 State of Michigan and all its Political Subdivisions [Member]	Dec. 31, 2013 State of Michigan and all its Political Subdivisions [Member]	Jun. 30, 2014 US States and Political Subdivisions Debt Securities [Member]	Dec. 31, 2013 US States and Political Subdivisions Debt Securities [Member]	Jun. 30, 2014 Securities Other Than US Government Agencies and the State of Michigan and Political Subdivisions [Member] Stockholders' Equity, Total [Member] Securities Issued Concentration Risk [Member]	Jun. 30, 2014 US Government Agency Debt Obligations and Mortgage-Backed Securities [Member]	Dec. 31, 2013 US Government Agency Debt Obligations and Mortgage-Backed Securities [Member]
Note 3 - Securities (Details) [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions					452	1
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 325,525,000		$ 88,446,000				$ 1,355,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	7,149,000		10,100,000				31,000
Available-for-sale Debt Securities, Amortized Cost Basis	471,333,000							114,800,000	17,400,000	36,400,000	36,300,000
Available-for-sale Securities	475,275,000	[1]	131,178,000	[1]			1,355,000	115,200,000	17,800,000
Concentration Risk, Percentage												0.00%
Available-for-sale Securities, Restricted													$ 272,600,000	$ 94,400,000

[1] See Note 13 for a description of the fair value hierarchy as well as a disclosure of levels for classes of financial assets and liabilities.