Note 3 - Investment Securities (Detail) - Amortized cost and fair value of securities, by contractual maturity (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Maturity in years:
Securities Available for Sale, Amortized Cost, 1 year or less	$ 79,377	$ 40,380
Securities Available for Sale, Fair Value, 1 year or less	80,036	40,686
Securities Held to Maturity, Amortized Cost, 1 year or less	10,458	10,265
Securities Held to Maturity, Fair Value, 1 year or less	10,733	10,496
Securities Available for Sale, Amortized Cost, Over 1 to 5 years	371,270	309,293
Securities Available for Sale, Fair Value, Over 1 to 5 years	375,009	312,480
Securities Held to Maturity, Amortized Cost, Over 1 to 5 years	166,385	167,162
Securities Held to Maturity, Fair Value, Over 1 to 5 years	170,445	171,769
Securities Available for Sale, Amortized Cost, Over 5 to 10 years	70,880	59,817
Securities Available for Sale, Fair Value, Over 5 to 10 years	74,190	63,540
Securities Held to Maturity, Amortized Cost, Over 5 to 10 years	265,198	227,603
Securities Held to Maturity, Fair Value, Over 5 to 10 years	272,601	236,608
Securities Available for Sale, Amortized Cost, Over 10 years	103,084	110,919
Securities Available for Sale, Fair Value, Over 10 years	111,321	120,467
Securities Held to Maturity, Amortized Cost, Over 10 years	281,220	279,004
Securities Held to Maturity, Fair Value, Over 10 years	284,975	286,973
Securities Available for Sale, Amortized Cost, Subtotal	624,611	520,409
Securities Available for Sale, Fair Value, Subtotal	640,556	537,173
Securities Held to Maturity, Amortized Cost, Subtotal	723,261	684,034
Securities Held to Maturity, Fair Value, Subtotal	738,754	705,846
Securities Available for Sale, Amortized Cost, Mortgage-backed securities and residential collateralized mortgage obligations	317,865	276,767
Securities Available for Sale, Fair Value, Mortgage-backed securities and residential collateralized mortgage obligations	322,713	282,182
Securities Held to Maturity, Amortized Cost, Mortgage-backed securities and residential collateralized mortgage obligations	439,097	472,007
Securities Held to Maturity, Fair Value, Mortgage-backed securities and residential collateralized mortgage obligations	446,887	478,711
Securities Available for Sale, Amortized Cost, Other securities	2,883	2,915
Securities Available for Sale, Fair Value, Other securities	8,907	6,281
Securities Available for Sale, Amortized Cost, Total	945,359	800,091
Securities Available for Sale, Fair Value, Total	972,176	825,636
Securities Held to Maturity, Amortized Cost, Total	1,162,358	1,156,041
Securities Held to Maturity, Fair Value, Total	$ 1,185,641	$ 1,184,557

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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