OTHER COMPREHENSIVE INCOME (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	$ 2,571,617
Other comprehensive income before reclassifications	5,159
Amounts reclassified from AOCI	(173)
Net current period other comprehensive income	4,986
Balance at end of period	4,392,438
Unrealized Net Gains (Losses) on Securities Available for Sale [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(18,222)
Other comprehensive income before reclassifications	6,739
Amounts reclassified from AOCI	(14)
Net current period other comprehensive income	6,725
Balance at end of period	(11,497)
Unrealized Net Gains (Losses) on Derivative Instruments [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	5,254
Other comprehensive income before reclassifications	(2,390)
Amounts reclassified from AOCI	(159)
Net current period other comprehensive income	(2,549)
Balance at end of period	2,705
Unrecognized Pension and Postretirement Obligations [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(48,401)
Other comprehensive income before reclassifications	810
Amounts reclassified from AOCI	0
Net current period other comprehensive income	810
Balance at end of period	(47,591)
Accumulated Other Comprehensive Income (Loss) [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(61,369)
Balance at end of period	$ (56,383)