OTHER COMPREHENSIVE INCOME (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	$ 4,409,194
Balance at end of period	4,433,453
Unrealized Net Losses on Debt Securities Available for Sale [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(29,626)
Other comprehensive (loss) income before reclassifications	(29,787)
Amounts reclassified from AOCI	0
Net current period other comprehensive (loss) income	(29,787)
Balance at end of period	(59,413)
Unrealized Net Gains (Losses) on Derivative Instruments [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	5,407
Other comprehensive (loss) income before reclassifications	3,804
Amounts reclassified from AOCI	(173)
Net current period other comprehensive (loss) income	3,631
Balance at end of period	9,038
Unrecognized Pension and Postretirement Obligations [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(58,833)
Other comprehensive (loss) income before reclassifications	484
Amounts reclassified from AOCI	0
Net current period other comprehensive (loss) income	484
Balance at end of period	(58,349)
Accumulated Other Comprehensive Income (Loss) [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(83,052)
Other comprehensive (loss) income before reclassifications	(25,499)
Amounts reclassified from AOCI	(173)
Net current period other comprehensive (loss) income	(25,672)
Balance at end of period	$ (108,724)