Note 18 - Fair Value Measurements (Detail) - Estimated Fair Values and Related Carrying Amounts of Financial Instruments (USD $)	Jun. 30, 2012		Mar. 31, 2012	Dec. 31, 2011		Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010
Financial assets:
Cash and cash equivalents	$ 545,582,000			$ 570,206,000
Held-to-maturity securities	525,522,000			525,444,000
Held-to-maturity securities	531,500,000			532,206,000
Mortgage loans held for sale	15,495,000			22,976,000
Interest receivable	12,975,000			15,126,000
Loans not covered by loss share agreements	1,586,339,000			1,549,661,000
Loans covered by FDIC loss share agreements	114,189,000	[1]	129,755,000	158,075,000	[1]	192,899,000	208,774,000	231,600,000
FDIC indemnification asset	35,038,000			47,683,000
Financial liabilities:
Non-interest bearing transaction accounts	517,854,000			532,259,000
Time deposits	820,476,000			878,634,000
Interest bearing transaction accounts and savings deposits	1,290,954,000			1,239,504,000
Time deposits	820,476,000			878,634,000
Federal funds purchased and securities sold under agreements to repurchase	70,220,000			114,766,000
Other borrowings	90,866,000			90,170,000
Subordinated debentures	30,930,000			30,930,000
Interest payable	1,602,000			1,437,000
Non-interest Bearing Accounts [Member] | Fair Value, Inputs, Level 2 [Member]
Financial liabilities:
Non-interest bearing transaction accounts	517,854,000
Interest bearing transaction accounts and savings deposits	517,854,000
Non-interest Bearing Accounts [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Financial liabilities:
Non-interest bearing transaction accounts	517,854,000			532,259,000
Interest bearing transaction accounts and savings deposits	517,854,000			532,259,000
Non-interest Bearing Accounts [Member]
Financial liabilities:
Non-interest bearing transaction accounts	517,854,000			532,259,000
Interest Bearing Accounts [Member] | Fair Value, Inputs, Level 2 [Member]
Financial liabilities:
Non-interest bearing transaction accounts	1,290,954,000
Interest bearing transaction accounts and savings deposits	1,290,954,000
Interest Bearing Accounts [Member] | Fair Value, Inputs, Level 3 [Member]
Financial liabilities:
Time deposits	824,838,000
Time deposits	824,838,000
Interest Bearing Accounts [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Financial liabilities:
Non-interest bearing transaction accounts	1,290,954,000			1,239,504,000
Time deposits	824,838,000			882,244,000
Interest bearing transaction accounts and savings deposits	1,290,954,000			1,239,504,000
Time deposits	824,838,000			882,244,000
Interest Bearing Accounts [Member]
Financial liabilities:
Time deposits	820,476,000			878,634,000
Interest bearing transaction accounts and savings deposits	1,290,954,000			1,239,504,000
Time deposits	820,476,000			878,634,000
Fair Value, Inputs, Level 1 [Member]
Financial assets:
Cash and cash equivalents	545,582,000
Fair Value, Inputs, Level 2 [Member]
Financial assets:
Held-to-maturity securities	531,500,000
Interest receivable	12,975,000
Financial liabilities:
Federal funds purchased and securities sold under agreements to repurchase	70,220,000
Other borrowings	95,695,000
Subordinated debentures	26,314,000
Interest payable	1,602,000
Fair Value, Inputs, Level 3 [Member]
Financial assets:
Mortgage loans held for sale	15,495,000
Loans not covered by loss share agreements	1,583,598,000
Loans covered by FDIC loss share agreements	112,768,000
FDIC indemnification asset	35,038,000
Estimate of Fair Value, Fair Value Disclosure [Member]
Financial assets:
Cash and cash equivalents	545,582,000			570,206,000
Held-to-maturity securities	531,500,000			532,206,000
Mortgage loans held for sale	15,495,000			22,976,000
Interest receivable	12,975,000			15,126,000
Loans not covered by loss share agreements	1,583,598,000			1,548,034,000
Loans covered by FDIC loss share agreements	112,768,000			157,424,000
FDIC indemnification asset	35,038,000			47,683,000
Financial liabilities:
Federal funds purchased and securities sold under agreements to repurchase	70,220,000			114,766,000
Other borrowings	95,695,000			96,129,000
Subordinated debentures	26,314,000			30,833,000
Interest payable	$ 1,602,000			$ 1,437,000

[1] These loans were not classified as non-performing assets at June 30, 2012 or December 31, 2011, as the loans are accounted for on a pooled basis and the pools are considered to be performing. Therefore, interest income, through accretion of the difference between the carrying amount of the loans and the expected cash flows, is being recognized on all purchased impaired loans. The loans are grouped in pools sharing common risk characteristics and were treated in the aggregate when applying various valuation techniques.