INCOME TAXES (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current Income Tax Expense (Benefit) [Abstract]
Federal									$ 21,127	$ 21,232	$ 22,475
State and City									3,235	8,121	7,806
Current Income Tax Expense (Benefit), Total									24,362	29,353	30,281
Deferred Income Tax Expense (Benefit) [Abstract]
Federal									2,269	540	362
State and City									4,614	231	(1,302)
Deferred Income Tax Expense (Benefit), Total									6,883	771	(940)
Federal, Total									23,396	21,772	22,837
State and City, Total									7,849	8,352	6,504
Income Tax Expense (Benefit), Total	$ 8,241	$ 7,092	$ 7,987	$ 7,925	$ 7,628	$ 7,788	$ 7,531	$ 7,177	31,245	30,124	29,341
Income Tax Reconciliation [Abstract]
Tax at Federal statutory rate									26,606	26,029	25,511
State and local taxes, net of federal income tax benefit									5,102	5,466	4,228
Benefit plan differences									(59)	(156)	(445)
Adjustments for prior period tax returns									590	(164)	422
Investment in BOLI									(842)	(610)	(585)
Other, net									(152)	(441)	210
Income Tax Expense (Benefit), Total	8,241	$ 7,092	$ 7,987	$ 7,925	7,628	$ 7,788	$ 7,531	$ 7,177	$ 31,245	$ 30,124	$ 29,341
Effective tax rate (in hundredths)									41.10%	40.51%	40.25%
Deferred Tax Assets [Abstract]
Allowance for loan losses	8,303				8,261				$ 8,303	$ 8,261
Employee benefit plans	18,849				19,487				18,849	19,487
Credit component of OTTI	0				4,023				0	4,023
Tax effect of other components of income on investment securities and MBS tax note	722				109				722	109
Other	1,768				1,515				1,768	1,515
Total deferred tax assets	29,642				33,395				29,642	33,395
Deferred Tax Liabilities [Abstract]
Difference in book and tax carrying value of fixed assets	667				983				667	983
Difference in book and tax basis of unearned loan fees	2,761				0				2,761	0
Other	448				16				448	16
Total deferred tax liabilities	3,876				999				3,876	999
Net deferred tax asset (recorded in other assets)	25,766				32,396				25,766	32,396
Bad debt reserve subject to recapture [Abstract]
Accumulated bad debt reserves for which no provision for income tax was required to be recorded	$ 15,158				$ 15,158				15,158	15,158
Additional income tax expense due to bad debt recapture									$ 6,844	$ 6,844