Note 6 - Investment Securities (Details) - Investment Securities (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Securities Available-for-Sale
Securities Available-for-sale, Amortized Cost	$ 1,355,056	$ 1,637,965
Securities Available-for-sale, Gross Unrealized Gains	7,710	18,511
Securities Available-for-sale, Gross Unrealized Losses	22,674	69,808
Securities Available-for-sale, Fair Value	1,340,092	1,586,668
US Treasury Securities [Member]
Securities Available-for-Sale
Securities Available-for-sale, Amortized Cost	539,919	460,095
Securities Available-for-sale, Gross Unrealized Gains	198	99
Securities Available-for-sale, Gross Unrealized Losses	29	1
Securities Available-for-sale, Fair Value	540,088	460,193
Collateralized Mortgage Backed Securities [Member]
Securities Available-for-Sale
Securities Available-for-sale, Amortized Cost	703,312	1,010,294
Securities Available-for-sale, Gross Unrealized Gains	1,085	7,049
Securities Available-for-sale, Gross Unrealized Losses	21,073	64,529
Securities Available-for-sale, Fair Value	683,324	952,814
Collateralized Mortgage Obligations [Member]
Securities Available-for-Sale
Securities Available-for-sale, Amortized Cost	80	5,929
Securities Available-for-sale, Gross Unrealized Gains		231
Securities Available-for-sale, Gross Unrealized Losses	34	54
Securities Available-for-sale, Fair Value	46	6,106
Corporate Debt Securities [Member]
Securities Available-for-Sale
Securities Available-for-sale, Amortized Cost	94,941	154,955
Securities Available-for-sale, Gross Unrealized Gains	751	298
Securities Available-for-sale, Gross Unrealized Losses	1,355	4,949
Securities Available-for-sale, Fair Value	94,337	150,304
Mutual Funds [Member]
Securities Available-for-Sale
Securities Available-for-sale, Amortized Cost	6,000	6,000
Securities Available-for-sale, Gross Unrealized Losses	183	275
Securities Available-for-sale, Fair Value	5,817	5,725
Preferred Stock of Government Sponsored Entities [Member]
Securities Available-for-Sale
Securities Available-for-sale, Amortized Cost	7,196	569
Securities Available-for-sale, Gross Unrealized Gains	2,056	10,834
Securities Available-for-sale, Fair Value	9,252	11,403
Other Equity Securities [Member]
Securities Available-for-Sale
Securities Available-for-sale, Amortized Cost	3,608
Securities Available-for-sale, Gross Unrealized Gains	3,620
Securities Available-for-sale, Fair Value	7,228
Asset-backed Securities [Member]
Securities Available-for-Sale
Securities Available-for-sale, Amortized Cost		123
Securities Available-for-sale, Fair Value		$ 123