OTHER COMPREHENSIVE INCOME (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	$ 4,409,194
Balance at end of period	4,473,242
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	(38,660)
Amounts reclassified from AOCI	(24)
Net current period other comprehensive (loss) income	(38,684)
Balance at end of period	(68,310)
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	5,600
Amounts reclassified from AOCI	(721)
Net current period other comprehensive (loss) income	4,879
Balance at end of period	10,286
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	972
Amounts reclassified from AOCI	0
Net current period other comprehensive (loss) income	972
Balance at end of period	(57,861)
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	(32,088)
Amounts reclassified from AOCI	(745)
Net current period other comprehensive (loss) income	(32,833)
Balance at end of period	$ (115,885)