Note 6 - Investment Securities (Details) - Temporarily Impaired Securities (USD $)	Mar. 31, 2015	Dec. 31, 2014
Securities Available-for-Sale
Securities Available-for-Sale - Less than 12 Months - Fair Value	$ 147,911,000	$ 376,601,000
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	3,919,000	3,998,000
Securities Available-for-Sale - 12 Months or longer - Fair Value	49,804	494,754
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	1,277,000	7,801,000
Securities Available-for-Sale - Fair Value	197,715,000	871,355,000
Securities Available-for-Sale - Unrealized Losses	5,196	11,799
Collateralized Mortgage Backed Securities [Member]
Securities Available-for-Sale
Securities Available-for-Sale - Less than 12 Months - Fair Value	145,297,000
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	332,000
Securities Available-for-Sale - 12 Months or longer - Fair Value	7
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	1,000
Securities Available-for-Sale - Fair Value	145,304,000
Securities Available-for-Sale - Unrealized Losses	333
Collateralized Mortgage Obligations [Member]
Securities Available-for-Sale
Securities Available-for-Sale - 12 Months or longer - Fair Value	41	45
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	32,000	34,000
Securities Available-for-Sale - Fair Value	41,000	45,000
Securities Available-for-Sale - Unrealized Losses	32	34
Corporate Debt Securities [Member]
Securities Available-for-Sale
Securities Available-for-Sale - 12 Months or longer - Fair Value	43,835	63,753
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	1,165,000	1,247,000
Securities Available-for-Sale - Fair Value	43,835,000	63,753,000
Securities Available-for-Sale - Unrealized Losses	1,165	1,247
Mutual Funds [Member]
Securities Available-for-Sale
Securities Available-for-Sale - 12 Months or longer - Fair Value	5,921	5,866
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses	79,000	134,000
Securities Available-for-Sale - Fair Value	5,921,000	5,866,000
Securities Available-for-Sale - Unrealized Losses	79	134
Preferred Stock of Government Sponsored Entities [Member]
Securities Available-for-Sale
Securities Available-for-Sale - Less than 12 Months - Fair Value	2,597,000	2,448,000
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	3,584,000	3,733,000
Securities Available-for-Sale - Fair Value	2,597,000	2,448,000
Securities Available-for-Sale - Unrealized Losses	3,584	3,733
Other Equity Securities [Member]
Securities Available-for-Sale
Securities Available-for-Sale - Less than 12 Months - Fair Value	17,000
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses	3,000
Securities Available-for-Sale - Fair Value	17,000
Securities Available-for-Sale - Unrealized Losses	3
US Treasury Securities [Member]
Securities Available-for-Sale
Securities Available-for-Sale - Less than 12 Months - Fair Value		374,153,000
Securities Available-for-Sale - Less than 12 Months - Unrealized Losses		265,000
Securities Available-for-Sale - Fair Value		374,153,000
Securities Available-for-Sale - Unrealized Losses		265
Mortgage Backed Securities Non Agency [Member]
Securities Available-for-Sale
Securities Available-for-Sale - 12 Months or longer - Fair Value		425,090
Securities Available-for-Sale - 12 Months or longer - Unrealized Losses		6,386,000
Securities Available-for-Sale - Fair Value		425,090,000
Securities Available-for-Sale - Unrealized Losses		$ 6,386

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