Note 17 - Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2015

Fair Value Disclosures [Abstract]

Fair Value, by Balance Sheet Grouping [Table Text Block]

	December 31, 2015				December 31, 2014
	Carrying				Carrying
	Amount		Fair Value		Amount		Fair Value
	(In thousands)
Financial Assets
Cash and due from banks	$	180,130	$	180,130	$	176,830	$	176,830
Short-term investments		536,880		536,880		489,614		489,614
Securities available-for-sale		1,586,352		1,586,352		1,318,935		1,318,935
Loans held for sale		6,676		6,676		973		1,225
Loans, net		10,016,227		9,938,810		8,740,268		8,688,072
Investment in Federal Home Loan Bank stock		17,250		17,250		30,785		30,785
Warrants		62		62		27		27

	Notional				Notional
	Amount		Fair Value		Amount		Fair Value
Foreign exchange contracts		100,602		3,339		167,005		1,876

	Carrying				Carrying
	Amount		Fair Value		Amount		Fair Value
Financial Liabilities
Deposits	$	10,509,087		10,509,879	$	8,783,460	$	8,785,342
Securities sold under agreements to repurchase		400,000		413,417		450,000		473,816
Advances from Federal Home Loan Bank		275,000		274,488		425,000		424,974
Other borrowings		18,593		16,684		19,934		17,978
Long-term debt		119,136		58,420		119,136		59,425

	Notional				Notional
	Amount		Fair Value		Amount		Fair Value
Option contracts	$	9,396	$	28	$	-	$	-
Foreign exchange contracts	$	115,418	$	4,124	$	178,868	$	5,007
Interest rate swaps		459,416		6,496		300,480		4,626

	Notional					Notional
	Amount		Fair Value			Amount		Fair Value
Off-Balance Sheet Financial Instruments
Commitments to extend credit	$	1,971,848	$	(5,570	)	$	2,071,766	$	(3,442	)
Standby letters of credit		49,081		(194	)		53,910		(243	)
Other letters of credit		38,131		(22	)		48,142		(29	)
Bill of lading guarantees		454		(1	)		108		-

Schedule of Fair Value of Financial Instruments [Table Text Block]

	As of December 31, 2015
	Estimated
	Fair Value
	Measurements		Level 1		Level 2		Level 3
	(In thousands)
Financial Assets
Cash and due from banks	$	180,130	$	180,130	$	-	$	-
Short-term investments		536,880		536,880		-		-
Securities available-for-sale		1,586,352		290,121		1,296,231		-
Loans held-for-sale		6,676		-		-		6,676
Loans, net		9,938,810		-		-		9,938,810
Investment in Federal Home Loan Bank stock		17,250		-		17,250		-
Warrants		62		-		-		62
Financial Liabilities
Deposits		10,509,879		-		-		10,509,879
Securities sold under agreement to repurchase		413,417		-		413,417		-
Advances from Federal Home Loan Bank		274,488		-		-		274,488
Other borrowings		16,684		-		-		16,684
Long-term debt		58,420		-		58,420		-

	As of December 31, 2014
	Estimated
	Fair Value
	Measurements		Level 1		Level 2		Level 3
	(In thousands)
Financial Assets
Cash and due from banks	$	176,830	$	176,830	$	-	$	-
Short-term investments		489,614		489,614		-		-
Securities available-for-sale		1,318,935		669,870		649,065		-
Loans held-for-sale		1,225		-		-		1,225
Loans, net		8,688,072		-		-		8,688,072
Investment in Federal Home Loan Bank stock		30,785		-		30,785		-
Warrants		27		-		-		27
Financial Liabilities
Deposits		8,785,342		-		-		8,785,342
Securities sold under agreement to repurchase		473,816		-		473,816		-
Advances from Federal Home Loan Bank		424,974		-		424,974		-
Other borrowings		17,978		-		-		17,978
Long-term debt		59,425		-		59,425		-