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, 2013	Dec. 31, 2012
Securities available-for-sale
Securities Available-for-Sale	$ 2,190,296	$ 1,291,480
US Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Securities Available-for-Sale	360,114	509,971
US Treasury Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	0
US Treasury Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	0
US Treasury Securities [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Securities Available-for-Sale	360,114	509,971
US Treasury Securities [Member]
Securities available-for-sale
Securities Available-for-Sale	360,114	509,971
State and Municipal Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Securities Available-for-Sale	0
State and Municipal Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities Available-for-Sale	63,458
State and Municipal Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Securities Available-for-Sale	0
State and Municipal Securities [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Securities Available-for-Sale	63,458
State and Municipal Securities [Member]
Securities available-for-sale
Securities Available-for-Sale	63,458
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	1,490,598	416,694
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	1,490,598	416,694
Collateralized Mortgage Backed Securities [Member]
Securities available-for-sale
Securities Available-for-Sale	1,490,598	416,694
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	8,946	10,168
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	8,946	10,168
Collateralized Mortgage Obligations [Member]
Securities available-for-sale
Securities Available-for-Sale	8,946	10,168
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	132	141
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	132	141
Asset-backed Securities [Member]
Securities available-for-sale
Securities Available-for-Sale	132	141
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	256,457	335,977
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	256,457	335,977
Corporate Debt Securities [Member]
Securities available-for-sale
Securities Available-for-Sale	256,457	335,977
Mutual Funds Member | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Securities Available-for-Sale	6,035	6,079
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	6,035	6,079
Mutual Funds Member
Securities available-for-sale
Securities Available-for-Sale	6,035	6,079
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	4,556	2,335
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	4,556	2,335
Preferred Stock Of Government Sponsored Entities Member
Securities available-for-sale
Securities Available-for-Sale	4,556	2,335
Trading Securities Member | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Total Assets	0	0
Trading Securities Member | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Total Assets	4,758	4,703
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	4,758	4,703
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	98	104
Warrant [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Total Assets	98	104
Option Contracts Member | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Total Assets	0	0
Liabilities
Total Liabilities	0	0
Option Contracts Member | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Total Assets	8	0
Liabilities
Total Liabilities	2	2
Option Contracts Member | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Total Assets	0	0
Liabilities
Total Liabilities	0	0
Option Contracts Member | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Total Assets	8	0
Liabilities
Total Liabilities	2	2
Foreign Exchange Contract [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Total Assets	0	0
Liabilities
Total Liabilities	0	0
Foreign Exchange Contract [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Total Assets	2,987	2,924
Liabilities
Total Liabilities	1,850	1,586
Foreign Exchange Contract [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Total Assets	0	0
Liabilities
Total Liabilities	0	0
Foreign Exchange Contract [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Total Assets	2,987	2,924
Liabilities
Total Liabilities	1,850	1,586
Trust Preferred Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Securities Available-for-Sale		10,115
Trust Preferred Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities Available-for-Sale		0
Trust Preferred Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Securities Available-for-Sale		0
Trust Preferred Securities [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Securities Available-for-Sale		10,115
Trust Preferred Securities [Member]
Securities available-for-sale
Securities Available-for-Sale		10,115
Other Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Securities Available-for-Sale		0
Other Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities Available-for-Sale		0
Other Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Securities Available-for-Sale		0
Other Equity Securities [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Securities Available-for-Sale		0
Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Securities Available-for-Sale	366,149	526,165
Total Assets	366,149	526,165
Liabilities
Total Liabilities	0	0
Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities Available-for-Sale	1,824,147	765,315
Total Assets	1,831,900	772,942
Liabilities
Total Liabilities	1,852	1,588
Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Securities Available-for-Sale	0	0
Total Assets	98	104
Liabilities
Total Liabilities	0	0
Estimate of Fair Value, Fair Value Disclosure [Member]
Securities available-for-sale
Securities Available-for-Sale	2,190,296	1,291,480
Total Assets	2,198,147	1,299,211
Liabilities
Total Liabilities	$ 1,852	$ 1,588