Note 6 - Investment Securities (Detail) - Temporarily Impaired Securities (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Securities Available-for-Sale - Less than 12 Months - Fair Value	$ 461,542	$ 253,430
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	9,929	14,586
Securities Available-for-Sale - Less than 12 Months - No of Issuances	162,078,000	180,347,000
Securities Available-for-Sale - 12 Months or longer - Fair Value	14,317	18,204
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	623,620	433,777
Securities Available-for-Sale- 12 Months or longer - No. of Issuances	24,246,000	32,790,000
Investment Securities - Less than 12 Months - Fair Value	461,542	253,430
Investment Securities - Less than 12 Months - Unrealized Losses	9,929	14,586
Investment Securities - Less than 12 Months - No of Issuances	162,078,000	180,347,000
Investment Securities - 12 Months or longer - Fair Value	14,317	18,204
Investment Securities- 12 Months or longer - Unrealized Losses	623,620	433,777
Investment Securities - 12 Months or longer - No. of Issuances	24,246,000	32,790,000
Corporate Debt Securities [Member]
Securities Held-to-maturity - Less than 12 Months - Fair Value	9,925	9,635
Securities Held-to-maturity - Less than 12 Months - Unrealized Losses	46	337
Securities Held-to-maturity - 12 Months or longer - Fair Value	0	0
Securities Held-to-maturity - 12 Months or longer - Unrealized Losses	9,925	9,635
Securities Held-to-maturity - 12 Months or longer - No. of Issuances	46,000	337,000
Securities Available-for-Sale - Less than 12 Months - Fair Value	145,771	185,577
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	9,180	14,201
Securities Available-for-Sale - Less than 12 Months - No of Issuances	160,783,000	172,857,000
Securities Available-for-Sale - 12 Months or longer - Fair Value	14,217	17,528
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	306,554	358,434
Securities Available-for-Sale- 12 Months or longer - No. of Issuances	23,397,000	31,729,000
Investment Securities - Less than 12 Months - Fair Value	145,771	185,577
Investment Securities - Less than 12 Months - Unrealized Losses	9,180	14,201
Investment Securities - Less than 12 Months - No of Issuances	160,783,000	172,857,000
Investment Securities - 12 Months or longer - Fair Value	14,217	17,528
Investment Securities- 12 Months or longer - Unrealized Losses	306,554	358,434
Investment Securities - 12 Months or longer - No. of Issuances	23,397,000	31,729,000
Total [Member]
Securities Held-to-maturity - Less than 12 Months - Fair Value	9,925	9,635
Securities Held-to-maturity - Less than 12 Months - Unrealized Losses	46	337
Securities Held-to-maturity - 12 Months or longer - Fair Value		0
Securities Held-to-maturity - 12 Months or longer - Unrealized Losses	9,925	9,635
Securities Held-to-maturity - 12 Months or longer - No. of Issuances	46,000	337,000
Securities Available-for-Sale - Less than 12 Months - Fair Value	451,617	243,795
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	9,883	14,249
Securities Available-for-Sale - Less than 12 Months - No of Issuances	162,078,000	180,347,000
Securities Available-for-Sale - 12 Months or longer - Fair Value	14,317	18,204
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	613,695	424,142
Securities Available-for-Sale- 12 Months or longer - No. of Issuances	24,200,000	32,453,000
Investment Securities - Less than 12 Months - Fair Value	451,617	243,795
Investment Securities - Less than 12 Months - Unrealized Losses	9,883	14,249
Investment Securities - Less than 12 Months - No of Issuances	162,078,000	180,347,000
Investment Securities - 12 Months or longer - Fair Value	14,317	18,204
Investment Securities- 12 Months or longer - Unrealized Losses	613,695	424,142
Investment Securities - 12 Months or longer - No. of Issuances	24,200,000	32,453,000
US Treasury Securities [Member]
Securities Available-for-Sale - Less than 12 Months - Fair Value	99,855
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	49
Securities Available-for-Sale - 12 Months or longer - Fair Value	0
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	99,855
Securities Available-for-Sale- 12 Months or longer - No. of Issuances	49,000
Investment Securities - Less than 12 Months - Fair Value	99,855
Investment Securities - Less than 12 Months - Unrealized Losses	49
Investment Securities - 12 Months or longer - Fair Value	0
Investment Securities- 12 Months or longer - Unrealized Losses	99,855
Investment Securities - 12 Months or longer - No. of Issuances	49,000
U.S. Government Sponsored Entities [Member]
Securities Available-for-Sale - Less than 12 Months - Fair Value	49,894	49,993
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	106	7
Securities Available-for-Sale - 12 Months or longer - Fair Value	0	0
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	49,894	49,993
Securities Available-for-Sale- 12 Months or longer - No. of Issuances	106,000	7,000
Investment Securities - Less than 12 Months - Fair Value	49,894	49,993
Investment Securities - Less than 12 Months - Unrealized Losses	106	7
Investment Securities - 12 Months or longer - Fair Value	0	0
Investment Securities- 12 Months or longer - Unrealized Losses	49,894	49,993
Investment Securities - 12 Months or longer - No. of Issuances	106,000	7,000
Collateralized Mortgage Backed Securities [Member]
Securities Available-for-Sale - Less than 12 Months - Fair Value	154,114	564
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	532	4
Securities Available-for-Sale - Less than 12 Months - No of Issuances	535,000	35,000
Securities Available-for-Sale - 12 Months or longer - Fair Value	3	1
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	154,649	599
Securities Available-for-Sale- 12 Months or longer - No. of Issuances	535,000	5,000
Investment Securities - Less than 12 Months - Fair Value	154,114	564
Investment Securities - Less than 12 Months - Unrealized Losses	532	4
Investment Securities - Less than 12 Months - No of Issuances	535,000	35,000
Investment Securities - 12 Months or longer - Fair Value	3	1
Investment Securities- 12 Months or longer - Unrealized Losses	154,649	599
Investment Securities - 12 Months or longer - No. of Issuances	535,000	5,000
Mortgage Backed Securities Non Agency Member
Securities Available-for-Sale - Less than 12 Months - Fair Value	0	0
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	0	0
Securities Available-for-Sale - Less than 12 Months - No of Issuances	99,000	6,719,000
Securities Available-for-Sale - 12 Months or longer - Fair Value	2	431
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	99	6,719
Securities Available-for-Sale- 12 Months or longer - No. of Issuances	2,000	431,000
Investment Securities - Less than 12 Months - Fair Value	0	0
Investment Securities - Less than 12 Months - Unrealized Losses	0	0
Investment Securities - Less than 12 Months - No of Issuances	99,000	6,719,000
Investment Securities - 12 Months or longer - Fair Value	2	431
Investment Securities- 12 Months or longer - Unrealized Losses	99	6,719
Investment Securities - 12 Months or longer - No. of Issuances	2,000	431,000
Collateralized Mortgage Obligations [Member]
Securities Available-for-Sale - Less than 12 Months - Fair Value	0	0
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	0	0
Securities Available-for-Sale - Less than 12 Months - No of Issuances	503,000	570,000
Securities Available-for-Sale - 12 Months or longer - Fair Value	90	238
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	503	570
Securities Available-for-Sale- 12 Months or longer - No. of Issuances	90,000	238,000
Investment Securities - Less than 12 Months - Fair Value	0	0
Investment Securities - Less than 12 Months - Unrealized Losses	0	0
Investment Securities - Less than 12 Months - No of Issuances	503,000	570,000
Investment Securities - 12 Months or longer - Fair Value	90	238
Investment Securities- 12 Months or longer - Unrealized Losses	503	570
Investment Securities - 12 Months or longer - No. of Issuances	90,000	238,000
Asset-backed Securities [Member]
Securities Available-for-Sale - Less than 12 Months - Fair Value		0
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses		0
Securities Available-for-Sale - Less than 12 Months - No of Issuances	158,000	166,000
Securities Available-for-Sale - 12 Months or longer - Fair Value	5	6
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	158	166
Securities Available-for-Sale- 12 Months or longer - No. of Issuances	5,000	6,000
Investment Securities - Less than 12 Months - Fair Value		0
Investment Securities - Less than 12 Months - Unrealized Losses		0
Investment Securities - Less than 12 Months - No of Issuances	158,000	166,000
Investment Securities - 12 Months or longer - Fair Value	5	6
Investment Securities- 12 Months or longer - Unrealized Losses	158	166
Investment Securities - 12 Months or longer - No. of Issuances	5,000	6,000
Mutual Funds Member
Securities Available-for-Sale - Less than 12 Months - Fair Value	1,983	1,987
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	16	13
Securities Available-for-Sale - 12 Months or longer - Fair Value		0
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	1,983	1,987
Securities Available-for-Sale- 12 Months or longer - No. of Issuances	16,000	13,000
Investment Securities - Less than 12 Months - Fair Value	1,983	1,987
Investment Securities - Less than 12 Months - Unrealized Losses	16	13
Investment Securities - 12 Months or longer - Fair Value		0
Investment Securities- 12 Months or longer - Unrealized Losses	1,983	1,987
Investment Securities - 12 Months or longer - No. of Issuances	16,000	13,000
Trust Preferred Securities [Member]
Securities Available-for-Sale - Less than 12 Months - Fair Value		5,674
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses		24
Securities Available-for-Sale - 12 Months or longer - Fair Value		0
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses		5,674
Securities Available-for-Sale- 12 Months or longer - No. of Issuances		24,000
Investment Securities - Less than 12 Months - Fair Value		5,674
Investment Securities - Less than 12 Months - Unrealized Losses		24
Investment Securities - 12 Months or longer - Fair Value		0
Investment Securities- 12 Months or longer - Unrealized Losses		$ 5,674
Investment Securities - 12 Months or longer - No. of Issuances		24,000