Note 4 - Investment Securities (Details) - Investment Securities (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Securities Available-for-Sale
Securities Available-for-sale, Amortized Cost	$ 1,637,965	$ 1,290,676
Securities Available-for-sale, Gross Unrealized Gains	18,511	14,954
Securities Available-for-sale, Gross Unrealized Losses	69,808	14,150
Securities Available-for-sale, Fair Value	1,586,668	1,291,480
Total investment securities - Amortized Cost	1,637,695	2,064,444
Total investment securities - Gross Unrealized Gains	18,511	65,092
Total investment securities - Gross Unrealized Losses	69,808	14,150
Total investment securities - Fair Value	1,586,668	2,115,386
Securities Held-to-Maturity
Securities Held-to-Maturity, Amortized Cost		773,768
Securities Held-to-Maturity, Gross Unrealized Gains		50,138
Securities Held-to-Maturity, Fair Value		823,906
US Treasury Securities [Member]
Securities Available-for-Sale
Securities Available-for-sale, Amortized Cost	460,095	509,748
Securities Available-for-sale, Gross Unrealized Gains	99	228
Securities Available-for-sale, Gross Unrealized Losses	1	5
Securities Available-for-sale, Fair Value	460,193	509,971
Collateralized Mortgage Backed Securities [Member]
Securities Available-for-Sale
Securities Available-for-sale, Amortized Cost	1,010,294	404,505
Securities Available-for-sale, Gross Unrealized Gains	7,049	12,194
Securities Available-for-sale, Gross Unrealized Losses	64,529	5
Securities Available-for-sale, Fair Value	952,814	416,694
Securities Held-to-Maturity
Securities Held-to-Maturity, Amortized Cost		634,757
Securities Held-to-Maturity, Gross Unrealized Gains		40,801
Securities Held-to-Maturity, Fair Value		675,558
Collateralized Mortgage Obligations [Member]
Securities Available-for-Sale
Securities Available-for-sale, Amortized Cost	5,929	9,772
Securities Available-for-sale, Gross Unrealized Gains	231	430
Securities Available-for-sale, Gross Unrealized Losses	54	34
Securities Available-for-sale, Fair Value	6,106	10,168
Asset-backed Securities [Member]
Securities Available-for-Sale
Securities Available-for-sale, Amortized Cost	123	145
Securities Available-for-sale, Gross Unrealized Losses		4
Securities Available-for-sale, Fair Value	123	141
Corporate Debt Securities [Member]
Securities Available-for-Sale
Securities Available-for-sale, Amortized Cost	154,955	349,973
Securities Available-for-sale, Gross Unrealized Gains	298	106
Securities Available-for-sale, Gross Unrealized Losses	4,949	14,102
Securities Available-for-sale, Fair Value	150,304	335,977
Securities Held-to-Maturity
Securities Held-to-Maturity, Amortized Cost		9,974
Securities Held-to-Maturity, Gross Unrealized Gains		69
Securities Held-to-Maturity, Fair Value		10,043
Mutual Funds Member
Securities Available-for-Sale
Securities Available-for-sale, Amortized Cost	6,000	6,000
Securities Available-for-sale, Gross Unrealized Gains		79
Securities Available-for-sale, Gross Unrealized Losses	275
Securities Available-for-sale, Fair Value	5,725	6,079
Preferred Stock Of Government Sponsored Entities Member
Securities Available-for-Sale
Securities Available-for-sale, Amortized Cost	569	569
Securities Available-for-sale, Gross Unrealized Gains	10,834	1,766
Securities Available-for-sale, Fair Value	11,403	2,335
State and Municipal Securities [Member]
Securities Held-to-Maturity
Securities Held-to-Maturity, Amortized Cost		129,037
Securities Held-to-Maturity, Gross Unrealized Gains		9,268
Securities Held-to-Maturity, Fair Value		138,305
Trust Preferred Securities [Member]
Securities Available-for-Sale
Securities Available-for-sale, Amortized Cost		9,964
Securities Available-for-sale, Gross Unrealized Gains		151
Securities Available-for-sale, Fair Value		$ 10,115