INCOME TAXES (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current Income Tax Expense (Benefit) [Abstract]
Federal									$ 21,232	$ 22,475	$ 21,607
State and City									8,121	7,806	7,351
Current Income Tax Expense (Benefit), Total									29,353	30,281	28,958
Deferred Income Tax Expense (Benefit) [Abstract]
Federal									540	362	(1,395)
State and City									231	(1,302)	(673)
Deferred Income Tax Expense (Benefit), Total									771	(940)	(2,068)
Federal, Total									21,772	22,837	20,212
State and City, Total									8,352	6,504	6,678
Income Tax Expense (Benefit), Total	7,628	7,788	7,531	7,177	6,891	7,215	8,059	7,176	30,124	29,341	26,890
Income Tax Reconciliation [Abstract]
Tax at Federal statutory rate									26,029	25,511	23,519
State and local taxes, net of federal income tax benefit									5,466	4,228	4,341
Benefit plan differences									(156)	(445)	(114)
Adjustments for prior period tax returns									(164)	422	63
Investment in BOLI									(610)	(585)	(591)
Adjustment for unrecognized tax benefits									0	0	0
Other, net									(441)	210	(328)
Income Tax Expense (Benefit), Total	7,628	7,788	7,531	7,177	6,891	7,215	8,059	7,176	30,124	29,341	26,890
Effective tax rate (in hundredths)									40.51%	40.25%	40.02%
Deferred Tax Assets [Abstract]
Allowance for loan losses	8,261				9,518				8,261	9,518
Employee benefit plans	19,487				15,478				19,487	15,478
Credit component of OTTI	4,023				4,088				4,023	4,088
Tax effect of other components of income on securities deferred asset	109				0				109	0
Other	1,515				2,435				1,515	2,435
Total deferred tax assets	33,395				31,519				33,395	31,519
Deferred Tax Liabilities [Abstract]
Tax effect of other components of income on investment securities and MBS	0				559				0	559
Difference in book and tax carrying value of fixed assets	983				986				983	986
Other	16				109				16	109
Total deferred tax liabilities	999				1,654				999	1,654
Net deferred tax asset (recorded in other assets)	32,396				29,865				32,396	29,865
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