INCOME TAXES (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
FEDERAL [Abstract]
Current	$ 9,339	$ 21,556	$ 15,490
Deferred federal expense (benefit)	59	10,845	9,046
Total federal and deferred income federal tax expense (benefit)	9,398	32,401	24,536
STATE [Abstract]
Current	183	353	636
Deferred state expense (benefit)	0	0	0
Total state and deferred state income tax expense (benefit)	183	353	636
Income tax expense (benefit)	9,581	32,754	25,172
Continuing operations, income tax reconciliation [Abstract]
Computed tax expense at statutory rate	22,038	46,082	39,451
State income tax expense, net	119	228	413
Decrease in taxes resulting from [Abstract]
Tax-exempt loan and investment income	(12,927)	(13,861)	(14,890)
Amortization of goodwill and intangibles	(3)	(3)	(3)
Other, net	354	308	201
Income tax expense (benefit)	9,581	32,754	25,172
Deferred tax assets [Abstract]
Allowance for loan and lease losses	33,728	38,834
Tax credits	34,405	29,054
Net unrealized losses on investment securities available-for-sale	6,295	0
Deferred compensation	8,688	9,024
Net operating loss	702	1,470
Pension	1,532	5,407
Accrued expenses	5,796	4,101
Share-based compensation	3,044	2,487
(Loss) gain on subordinated debentures accounted for fair value	0	445
Write-downs on other real estate	30	103
Deferred tax assets	94,220	90,925
Deferred tax liabilities [Abstract]
Investment securities available-for-sale	0	22,108
Core deposit intangibles & acquisition related	5,904	6,551
Loan costs	7,352	6,761
Amortization	4,115	3,509
Depreciation	257	560
Deferred tax liabilities	17,628	39,489
Net deferred tax asset (included in other assets)	76,592	51,436
Years of net operating loss (NOL) carry forward, subject to expiration	12
Reconciliation of Unrecognized Tax Benefits [Roll forward]
Balance, beginning	1,886	2,401
Additions based on tax positions related to the current year	107	196
Additions for tax positions of prior years	0	0
Reductions for tax positions of prior years	(343)	(1)
Reductions as a result of lapse of applicable statute of limitations	(613)	(710)
Balance, Ending	$ 1,037	$ 1,886	$ 2,401