Note 10 - Borrowed Funds (Details) - Comparative Data for Securities Sold Under Agreements to Repurchase - Securities Sold under Agreements to Repurchase [Member] - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Note 10 - Borrowed Funds (Details) - Comparative Data for Securities Sold Under Agreements to Repurchase [Line Items]
Average amount outstanding during the year (1)	[1]	$ 400,822	$ 629,315	$ 972,329
Maximum amount outstanding at month-end (2)	[2]	400,000	700,000	1,200,000
Balance, December 31		$ 400,000	$ 450,000	$ 800,000
Rate, December 31		3.89%	3.85%	3.87%
Weighted average interest rate for the year		3.95%	3.92%	3.88%

[1] Average balances were computed using daily averages.

[2] Highest month-end balances were January 2015, January 2014, and January 2013.