Note 9 - Securities Sold Under Agreements to Repurchase (Detail) - Securities Sold Under Agreements to Repurchase (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Balance (in Dollars)	32,950	52,313
Weighted average interest rate	0.75%	0.97%
Securities Loaned or Sold under Agreements to Repurchase [Member] | Customers [Member] | Minimum [Member]
Range of interest rates paid	0.25%	0.25%	0.35%
Securities Loaned or Sold under Agreements to Repurchase [Member] | Customers [Member] | Maximum [Member]
Range of interest rates paid	0.55%	0.65%	0.65%
Securities Loaned or Sold under Agreements to Repurchase [Member] | Customers [Member] | At December 31 [Member]
Weighted average original maturity (days)	23 days	21 days	35 days
Securities Loaned or Sold under Agreements to Repurchase [Member] | Customers [Member] | During the Year [Member]
Weighted average interest rate	0.36%	0.43%	0.48%
Securities Loaned or Sold under Agreements to Repurchase [Member] | Customers [Member]
Balance (in Dollars)	32,950	47,313	23,016
Weighted average interest rate	0.36%	0.34%	0.45%
Maximum month-end balance (in Dollars)	43,199	51,991	55,998
Daily average balance (in Dollars)	39,318	42,911	47,674
Securities Loaned or Sold under Agreements to Repurchase [Member] | Dealers [Member] | Minimum [Member]
Range of interest rates paid	0.25%	0.13%	0.25%
Securities Loaned or Sold under Agreements to Repurchase [Member] | Dealers [Member] | Maximum [Member]
Range of interest rates paid	1.30%	1.30%	1.30%
Securities Loaned or Sold under Agreements to Repurchase [Member] | Dealers [Member] | At December 31 [Member]
Weighted average interest rate		1.30%	1.30%
Securities Loaned or Sold under Agreements to Repurchase [Member] | Dealers [Member] | During the Year [Member]
Weighted average interest rate	1.18%	1.27%	0.79%
Securities Loaned or Sold under Agreements to Repurchase [Member] | Dealers [Member]
Balance (in Dollars)		5,000	5,000
Weighted average original maturity (days)		731 days	731 days
Maximum month-end balance (in Dollars)	5,000	5,000	39,893
Daily average balance (in Dollars)	2,637	5,186	5,618