Note 6 - Investment Securities (Details) - Investment Securities (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended	12 Months Ended
	Mar. 31, 2013	Jun. 30, 2013	Dec. 31, 2012
Note 6 - Investment Securities (Details) - Investment Securities [Line Items]
Securities Available-for-sale, Amortized Cost		$ 2,044,312	$ 1,290,676
Securities Available-for-sale, Gross Unrealized Gains		26,943	14,954
Securities Available-for-sale, Gross Unrealized Losses	15,500	52,950	14,150
Available-for-sale Securities - Fair Value		2,018,305	1,291,480
Total investment securities - Amortized Cost		2,044,312	2,064,444
Total investment securities - Gross Unrealized Gains		26,943	65,092
Total investment securities - Gross Unrealized Losses		52,950	14,150
Total investment securities - Fair Value		2,018,305	2,115,386
Securities Held-to-Maturity, Amortized Cost			773,768
Securities Held-to-Maturity, Gross Unrealized Gains			50,138
Securities Held-to-Maturity, Gross Unrealized Losses			0
Securities Held-to-Maturity, Fair Value			823,906
US Treasury Securities [Member]
Note 6 - Investment Securities (Details) - Investment Securities [Line Items]
Securities Available-for-sale, Amortized Cost		409,849	509,748
Securities Available-for-sale, Gross Unrealized Gains		192	228
Securities Available-for-sale, Gross Unrealized Losses		6	5
Available-for-sale Securities - Fair Value		410,035	509,971
Collateralized Mortgage Backed Securities [Member]
Note 6 - Investment Securities (Details) - Investment Securities [Line Items]
Securities Available-for-sale, Amortized Cost		1,430,373	404,505
Securities Available-for-sale, Gross Unrealized Gains		20,153	12,194
Securities Available-for-sale, Gross Unrealized Losses		45,178	5
Available-for-sale Securities - Fair Value		1,405,348	416,694
Securities Held-to-Maturity, Amortized Cost			634,757
Securities Held-to-Maturity, Gross Unrealized Gains			40,801
Securities Held-to-Maturity, Gross Unrealized Losses			0
Securities Held-to-Maturity, Fair Value			675,558
Collateralized Mortgage Obligations [Member]
Note 6 - Investment Securities (Details) - Investment Securities [Line Items]
Securities Available-for-sale, Amortized Cost		7,438	9,772
Securities Available-for-sale, Gross Unrealized Gains		295	430
Securities Available-for-sale, Gross Unrealized Losses		65	34
Available-for-sale Securities - Fair Value		7,668	10,168
Asset-backed Securities [Member]
Note 6 - Investment Securities (Details) - Investment Securities [Line Items]
Securities Available-for-sale, Amortized Cost		132	145
Securities Available-for-sale, Gross Unrealized Gains		1	0
Securities Available-for-sale, Gross Unrealized Losses		0	4
Available-for-sale Securities - Fair Value		133	141
Corporate Debt Securities [Member]
Note 6 - Investment Securities (Details) - Investment Securities [Line Items]
Securities Available-for-sale, Amortized Cost		189,951	349,973
Securities Available-for-sale, Gross Unrealized Gains		415	106
Securities Available-for-sale, Gross Unrealized Losses		7,540	14,102
Available-for-sale Securities - Fair Value		182,826	335,977
Securities Held-to-Maturity, Amortized Cost			9,974
Securities Held-to-Maturity, Gross Unrealized Gains			69
Securities Held-to-Maturity, Gross Unrealized Losses			0
Securities Held-to-Maturity, Fair Value			10,043
Mutual Funds Member
Note 6 - Investment Securities (Details) - Investment Securities [Line Items]
Securities Available-for-sale, Amortized Cost		6,000	6,000
Securities Available-for-sale, Gross Unrealized Gains		0	79
Securities Available-for-sale, Gross Unrealized Losses		161	0
Available-for-sale Securities - Fair Value		5,839	6,079
Preferred Stock Of Government Sponsored Entities Member
Note 6 - Investment Securities (Details) - Investment Securities [Line Items]
Securities Available-for-sale, Amortized Cost		569	569
Securities Available-for-sale, Gross Unrealized Gains		5,887	1,766
Securities Available-for-sale, Gross Unrealized Losses		0	0
Available-for-sale Securities - Fair Value		6,456	2,335
State and Municipal Securities [Member]
Note 6 - Investment Securities (Details) - Investment Securities [Line Items]
Securities Held-to-Maturity, Amortized Cost			129,037
Securities Held-to-Maturity, Gross Unrealized Gains			9,268
Securities Held-to-Maturity, Gross Unrealized Losses			0
Securities Held-to-Maturity, Fair Value			138,305
Trust Preferred Securities [Member]
Note 6 - Investment Securities (Details) - Investment Securities [Line Items]
Securities Available-for-sale, Amortized Cost			9,964
Securities Available-for-sale, Gross Unrealized Gains			151
Securities Available-for-sale, Gross Unrealized Losses			0
Available-for-sale Securities - Fair Value			$ 10,115