Note 8 - Repurchase Agreements (Detail) - Repurchase Agreements Information - Additional (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Repurchase agreements	$ 1,108,942	$ 1,135,830
Maturity up to 30 days [Member]
Repurchase agreements	536,075	280,435
Maturity 31 to 60 Days [Member]
Repurchase agreements	552,091	629,311
Maturity 61 to 90 Days [Member]
Repurchase agreements	$ 20,776	$ 226,084

Carrying amount of assets sold under agreements to repurchase when the carrying amount (or market value, if higher than the carrying amount) of securities or other assets sold under repurchase agreements exceeds 10 percent of total assets.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(m)(1)(i)(A)(i))

-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph m

-Subparagraph 1

-Article 4

Name:	us-gaap_AssetsSoldUnderAgreementsToRepurchaseCarryingAmounts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant