Note 6 - Investment Securities (Details) - Temporarily Impaired Securities (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Securities Available-for-Sale
Investment Securities - Less than 12 Months - Fair Value	$ 1,016,903	$ 102,668
Investment Securities - Less than 12 Months - Unrealized Losses	45,587	2,538
Investment Securities - 12 Months or longer - Fair Value	153,194	254,276
Investment Securities- 12 Months or longer - Unrealized Losses	7,363	11,612
Investment Securities - Fair Value	1,170,097	356,944
Investment Securities - Unrealized Losses	52,950	14,150
US Treasury Securities [Member]
Securities Available-for-Sale
Securities Available-for-Sale - Less than 12 Months - Fair Value	99,918	49,969
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	6	5
Securities Available-for-Sale - 12 Months or longer - Fair Value	0	0
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	0	0
Securities Available-for-Sale - Fair Value	99,918	49,969
Securities Available-for-Sale - Unrealized Losses	6	5
Collateralized Mortgage Backed Securities [Member]
Securities Available-for-Sale
Securities Available-for-Sale - Less than 12 Months - Fair Value	901,227	231
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	45,174	1
Securities Available-for-Sale - 12 Months or longer - Fair Value	160	170
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	2	1
Securities Available-for-Sale - Fair Value	901,387	401
Securities Available-for-Sale - Unrealized Losses	45,176	2
Mortgage Backed Securities Non Agency Member
Securities Available-for-Sale
Securities Available-for-Sale - Less than 12 Months - Fair Value	94	0
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	2	0
Securities Available-for-Sale - 12 Months or longer - Fair Value	0	96
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	0	2
Securities Available-for-Sale - Fair Value	94	96
Securities Available-for-Sale - Unrealized Losses	2	2
Collateralized Mortgage Obligations [Member]
Securities Available-for-Sale
Securities Available-for-Sale - Less than 12 Months - Fair Value	67	0
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	2	0
Securities Available-for-Sale - 12 Months or longer - Fair Value	332	439
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	63	35
Securities Available-for-Sale - Fair Value	399	439
Securities Available-for-Sale - Unrealized Losses	65	35
Corporate Debt Securities [Member]
Securities Available-for-Sale
Securities Available-for-Sale - Less than 12 Months - Fair Value	9,758	52,468
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	242	2,532
Securities Available-for-Sale - 12 Months or longer - Fair Value	152,702	253,430
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	7,298	11,570
Securities Available-for-Sale - Fair Value	162,460	305,898
Securities Available-for-Sale - Unrealized Losses	7,540	14,102
Mutual Funds Member
Securities Available-for-Sale
Securities Available-for-Sale - Less than 12 Months - Fair Value	5,839
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	161
Securities Available-for-Sale - 12 Months or longer - Fair Value	0
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	0
Securities Available-for-Sale - Fair Value	5,839
Securities Available-for-Sale - Unrealized Losses	161
Total [Member]
Securities Available-for-Sale
Securities Available-for-Sale - Less than 12 Months - Fair Value	1,016,903	102,668
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	45,587	2,538
Securities Available-for-Sale - 12 Months or longer - Fair Value	153,194	254,276
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	7,363	11,612
Securities Available-for-Sale - Fair Value	1,170,097	356,944
Securities Available-for-Sale - Unrealized Losses	52,950	14,150
Securities Held-to-Maturity
Total securities held-to-maturity		0
Total securities held-to-maturity		0
Total securities held-to-maturity		0
Total securities held-to-maturity		0
Total securities held-to-maturity		0
Total securities held-to-maturity		0
Asset-backed Securities [Member]
Securities Available-for-Sale
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 - 12 Months or longer - Fair Value		141
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses		4
Securities Available-for-Sale - Fair Value		141
Securities Available-for-Sale - Unrealized Losses		$ 4