Note 10 - Borrowed Funds (Detail) - Comparative Data for Securities Sold Under Agreements to Repurchase (Securities Sold under Agreements to Repurchase [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Securities Sold under Agreements to Repurchase [Member]
Average amount outstanding during the year (1)	$ 1,361,475	[1]	$ 1,448,363	[1]	$ 1,560,215	[1]
Maximum amount outstanding at month-end (2)	1,400,000	[2]	1,559,000	[2]	1,566,000	[2]
Balance, December 31	$ 1,250,000		$ 1,400,000		$ 1,561,000
Rate, December 31	3.84%		4.14%		4.18%
Weighted average interest rate for the year	4.09%		4.19%		4.24%

[1] Average balances were computed using daily averages.

[2] Highest month-end balances were January 2012, January 2011, September 2010, and February 2009.