Note 21 - Condensed Financial Information (Parent Company Only) (Details) - Condensed Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 35,688	$ 23,231	$ 27,684
Items not requiring (providing) cash
Deferred income taxes	(9,029)	(4,618)	485
Changes in
Other assets	(17,313)	6,047	1,961
Net cash provided by operating activities	11,620	36,089	36,082
CASH FLOWS FROM INVESTING ACTIVITIES
Net purchases of premises and equipment	(11,293)	(4,772)	(2,268)
Net cash (used in) provided by investing activities	12,242	8,395	187,003
CASH FLOWS FROM FINANCING ACTIVITIES
Payment to repurchase common stock		(10,848)	(17,567)
Dividends paid	(15,359)	(13,707)	(13,495)
Net cash provided by (used in) financing activities	(227,333)	(42,901)	(255,494)
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(203,471)	1,583	(32,409)
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR	539,380	537,797	570,206
CASH AND CASH EQUIVALENTS, END OF YEAR	335,909	539,380	537,797
Parent Company [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	35,688	23,231	27,684
Items not requiring (providing) cash
Depreciation and amortization	139	145	167
Deferred income taxes	1,338	81	75
Equity in (distribution in excess of) undistributed net income of bank subsidiaries	(2,089)	(6,100)	11,897
Changes in
Other assets	(1,514)	19,978	(20,712)
Other liabilities	(1,103)	1,891
Net cash provided by operating activities	32,459	39,226	19,111
CASH FLOWS FROM INVESTING ACTIVITIES
Net purchases of premises and equipment	(5,435)	(174)	(84)
Additional (return from) investment in subsidiary	288	(27,400)	310
Sales (purchases) of available-for-sale securities	1,504	(1)
Cash paid in business combinations	(1,640)	(53,600)
Net cash (used in) provided by investing activities	(5,283)	(81,175)	226
CASH FLOWS FROM FINANCING ACTIVITIES
Repayment of subordinated debentures			(10,310)
(Repayment) issuance of long-term debt	(2,900)	46,000
Issuance of common stock, net	3,389	2,353	1,711
Payment to repurchase common stock		(10,848)	(17,567)
Dividends paid	(15,084)	(13,707)	(13,495)
Net cash provided by (used in) financing activities	(14,595)	23,798	(39,661)
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	12,581	(18,151)	(20,324)
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR	4,956	23,107	43,431
CASH AND CASH EQUIVALENTS, END OF YEAR	$ 17,537	$ 4,956	$ 23,107