Note 6 - Investment Securities (Details) - Temporarily Impaired Securities (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Securities Available-for-Sale
Investment Securities - Less than 12 Months - Fair Value	$ 898,809	$ 102,668
Investment Securities - Less than 12 Months - Unrealized Losses	46,150	2,538
Investment Securities - 12 Months or longer - Fair Value	123,203	254,276
Investment Securities- 12 Months or longer - Unrealized Losses	7,344	11,612
Investment Securities - Fair Value	1,022,012	356,944
Investment Securities - Unrealized Losses	53,494	14,150
Collateralized Mortgage Backed Securities [Member]
Securities Available-for-Sale
Securities Available-for-Sale - Less than 12 Months - Fair Value	882,851	231
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	45,944	1
Securities Available-for-Sale - 12 Months or longer - Fair Value	154	170
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	2	1
Securities Available-for-Sale - Fair Value	883,005	401
Securities Available-for-Sale - Unrealized Losses	45,946	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	1	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	1	2
Collateralized Mortgage Obligations [Member]
Securities Available-for-Sale
Securities Available-for-Sale - Less than 12 Months - Fair Value	68	0
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	1	0
Securities Available-for-Sale - 12 Months or longer - Fair Value	332	439
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	59	35
Securities Available-for-Sale - Fair Value	400	439
Securities Available-for-Sale - Unrealized Losses	60	35
Corporate Debt Securities [Member]
Securities Available-for-Sale
Securities Available-for-Sale - Less than 12 Months - Fair Value	9,984	52,468
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	16	2,532
Securities Available-for-Sale - 12 Months or longer - Fair Value	122,717	253,430
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	7,283	11,570
Securities Available-for-Sale - Fair Value	132,701	305,898
Securities Available-for-Sale - Unrealized Losses	7,299	14,102
Mutual Funds [Member]
Securities Available-for-Sale
Securities Available-for-Sale - Less than 12 Months - Fair Value	5,812
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	188
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	5,812
Securities Available-for-Sale - Unrealized Losses	188
Total [Member]
Securities Available-for-Sale
Securities Available-for-Sale - Less than 12 Months - Fair Value	898,809	102,668
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	46,150	2,538
Securities Available-for-Sale - 12 Months or longer - Fair Value	123,203	254,276
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	7,344	11,612
Securities Available-for-Sale - Fair Value	1,022,012	356,944
Securities Available-for-Sale - Unrealized Losses	53,494	14,150
US Treasury Securities [Member]
Securities Available-for-Sale
Securities Available-for-Sale - Less than 12 Months - Fair Value		49,969
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses		5
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		49,969
Securities Available-for-Sale - Unrealized Losses		5
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