SEGMENT INFORMATIO - Information about reportable segments (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Segment Reporting Information [Line Items]
Interest income	$ 150,831	$ 152,485
Net (charge) credit for transfer of funds	0	0
Interest expense	(26,183)	(26,838)
Net interest income (loss)	124,648	125,647
(Provision) release for loan and lease losses	(21,053)	(32,970)
Non-interest income (loss)	18,469	19,286
Direct non-interest expenses	(67,886)	(64,705)
Segment (loss) income	54,178	47,258
Average earnings assets	11,732,422	11,940,989
Mortgage Banking [Member]
Segment Reporting Information [Line Items]
Interest income	35,219	33,876
Net (charge) credit for transfer of funds	12,924	11,236
Interest expense	0	0
Net interest income (loss)	22,295	22,640
(Provision) release for loan and lease losses	(6,140)	(6,963)
Non-interest income (loss)	4,487	3,399
Direct non-interest expenses	(10,833)	(8,065)
Segment (loss) income	9,809	11,011
Average earnings assets	2,602,209	2,492,247
Consumer Retail Banking [Member]
Segment Reporting Information [Line Items]
Interest income	46,066	49,836
Net (charge) credit for transfer of funds	(3,882)	(3,684)
Interest expense	(6,162)	(5,657)
Net interest income (loss)	43,786	47,863
(Provision) release for loan and lease losses	(8,537)	(16,685)
Non-interest income (loss)	12,736	12,417
Direct non-interest expenses	(32,089)	(31,559)
Segment (loss) income	15,896	12,036
Average earnings assets	2,030,598	2,045,277
Commercial And Corporate [Member]
Segment Reporting Information [Line Items]
Interest income	33,548	34,803
Net (charge) credit for transfer of funds	6,096	3,795
Interest expense	0	0
Net interest income (loss)	27,452	31,008
(Provision) release for loan and lease losses	(7,548)	(9,093)
Non-interest income (loss)	561	524
Direct non-interest expenses	(9,664)	(7,979)
Segment (loss) income	10,801	14,460
Average earnings assets	2,552,200	3,028,358
Treasury And Investments [Member]
Segment Reporting Information [Line Items]
Interest income	13,760	13,067
Net (charge) credit for transfer of funds	(14,526)	(7,754)
Interest expense	(15,469)	(16,007)
Net interest income (loss)	12,817	4,814
(Provision) release for loan and lease losses	0	0
Non-interest income (loss)	(2,401)	(100)
Direct non-interest expenses	(1,050)	(1,339)
Segment (loss) income	9,366	3,375
Average earnings assets	2,777,748	2,764,058
United States Operations [Member]
Segment Reporting Information [Line Items]
Interest income	12,724	11,231
Net (charge) credit for transfer of funds	(612)	(3,593)
Interest expense	(3,689)	(4,339)
Net interest income (loss)	9,647	10,485
(Provision) release for loan and lease losses	(210)	2,133
Non-interest income (loss)	1,183	524
Direct non-interest expenses	(7,261)	(7,183)
Segment (loss) income	3,359	5,959
Average earnings assets	1,140,630	971,887
Virgin Islands Operations [Member]
Segment Reporting Information [Line Items]
Interest income	9,514	9,672
Net (charge) credit for transfer of funds	0	0
Interest expense	(863)	(835)
Net interest income (loss)	8,651	8,837
(Provision) release for loan and lease losses	1,382	(2,362)
Non-interest income (loss)	1,903	2,522
Direct non-interest expenses	(6,989)	(8,580)
Segment (loss) income	4,947	417
Average earnings assets	$ 629,037	$ 639,162