Note 11 - Fair Value Measurements (Detail) - Assets and Liabilities Measured at Fair Value on a Recurring Basis (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Securities available-for-sale
Securities Available-for-Sale	$ 1,353,742	$ 1,294,478
US Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Securities Available-for-Sale	99,855
US Treasury Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Securities Available-for-Sale	0
US Treasury Securities [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Securities Available-for-Sale	99,855
US Treasury Securities [Member]
Securities available-for-sale
Securities Available-for-Sale	99,855
U.S. Government Sponsored Entities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	0
U.S. Government Sponsored Entities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities Available-for-Sale	300,164	501,226
U.S. Government Sponsored Entities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	0
U.S. Government Sponsored Entities [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Securities Available-for-Sale	300,164	501,226
U.S. Government Sponsored Entities [Member]
Securities available-for-sale
Securities Available-for-Sale	300,164	501,226
State and Municipal Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	0
State and Municipal Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	1,928
State and Municipal Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	0
State and Municipal Securities [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Securities Available-for-Sale	0	1,928
State and Municipal Securities [Member]
Securities available-for-sale
Securities Available-for-Sale		1,928
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	0
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities Available-for-Sale	502,395	337,631
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	0
Collateralized Mortgage Backed Securities [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Securities Available-for-Sale	502,395	337,631
Collateralized Mortgage Backed Securities [Member]
Securities available-for-sale
Securities Available-for-Sale	502,395	337,631
Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	0
Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities Available-for-Sale	14,663	16,486
Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	0
Collateralized Mortgage Obligations [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Securities Available-for-Sale	14,663	16,486
Collateralized Mortgage Obligations [Member]
Securities available-for-sale
Securities Available-for-Sale	14,663	16,486
Asset-backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	0
Asset-backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities Available-for-Sale	158	166
Asset-backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	0
Asset-backed Securities [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Securities Available-for-Sale	158	166
Asset-backed Securities [Member]
Securities available-for-sale
Securities Available-for-Sale	159	166
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	0
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities Available-for-Sale	387,351	380,429
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	0
Corporate Debt Securities [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Securities Available-for-Sale	387,351	380,429
Corporate Debt Securities [Member]
Securities available-for-sale
Securities Available-for-Sale	387,350	380,429
Mutual Funds Member | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Securities Available-for-Sale	6,024	6,035
Mutual Funds Member | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	0
Mutual Funds Member | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	0
Mutual Funds Member | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Securities Available-for-Sale	6,024	6,035
Mutual Funds Member
Securities available-for-sale
Securities Available-for-Sale	6,024	6,035
Preferred Stock Of Government Sponsored Entities Member | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	0
Preferred Stock Of Government Sponsored Entities Member | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities Available-for-Sale	1,625	1,654
Preferred Stock Of Government Sponsored Entities Member | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	0
Preferred Stock Of Government Sponsored Entities Member | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Securities Available-for-Sale	1,625	1,654
Preferred Stock Of Government Sponsored Entities Member
Securities available-for-sale
Securities Available-for-Sale	1,625	1,654
Trust Preferred Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities Available-for-Sale	36,846	45,963
Trust Preferred Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	0
Trust Preferred Securities [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Securities Available-for-Sale	36,846	45,963
Trust Preferred Securities [Member]
Securities available-for-sale
Securities Available-for-Sale	36,846	45,963
Other Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Securities Available-for-Sale	4,661	2,960
Other Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	0
Other Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	0
Other Equity Securities [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Securities Available-for-Sale	4,661	2,960
Other Equity Securities [Member]
Securities available-for-sale
Securities Available-for-Sale	4,661	2,960
Trading Securities Member | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Total Assets	2	2
Trading Securities Member | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Total Assets	104,451	4,540
Trading Securities Member | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Total Assets	0	0
Trading Securities Member | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Total Assets	104,453	4,542
Warrant [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Total Assets	0	0
Warrant [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Total Assets	0	0
Warrant [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Total Assets	163	218
Warrant [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Total Assets	163	218
Option Contracts Member | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Total Assets	0	0
Total Liabilities	0	0
Option Contracts Member | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Total Assets	25	34
Total Liabilities	1	5
Option Contracts Member | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Total Assets	0	0
Total Liabilities	0	0
Option Contracts Member | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Total Assets	25	34
Total Liabilities	1	5
Foreign Exchange Contract [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Total Assets	0	0
Total Liabilities	0	0
Foreign Exchange Contract [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Total Assets	1,680	2,151
Total Liabilities	1,353	486
Foreign Exchange Contract [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Total Assets	0	0
Total Liabilities	0	0
Foreign Exchange Contract [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Total Assets	1,680	2,151
Total Liabilities	1,353	486
Interest Rate Swap [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Total Liabilities	0	0
Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Total Liabilities	1,845	2,634
Interest Rate Swap [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Total Liabilities	0	0
Interest Rate Swap [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Total Liabilities	1,845	2,634
Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Securities Available-for-Sale	110,540	8,995
Total Assets	110,542	8,997
Total Liabilities	0	0
Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities Available-for-Sale	1,243,202	1,285,483
Total Assets	1,349,358	1,292,208
Total Liabilities	3,199	3,125
Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	0
Total Assets	163	218
Total Liabilities	0	0
Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Securities Available-for-Sale	1,353,742	1,294,478
Total Assets	1,460,063	1,301,423
Total Liabilities	$ 3,199	$ 3,125