DEBT SECURITIES - Available-For-Sale Investments' Fair Value And Gross Unrealized Losses (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020
Schedule Of Available For Sale Securities [Line Items]
Fair Value Less than 12 months	$ 3,760,478		$ 4,601,661
Unrealized Losses Less than 12 months	311,398		76,269
Fair Value 12 months or more	2,168,487		1,008,607
Unrealized Losses 12 months or more	278,734		32,268
Total Fair Value	5,928,965		5,610,268
Total Unrealized Losses	590,132		108,537
Allowance for credit losses	252,152	$ 245,447	269,030	$ 324,958	$ 358,936	$ 385,887
Private label [Member]
Schedule Of Available For Sale Securities [Line Items]
Allowance for credit losses	300		800
U.S. Treasury and U.S. government agencies obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Fair Value Less than 12 months	1,530,493		1,717,340
Unrealized Losses Less than 12 months	89,224		25,401
Fair Value 12 months or more	1,005,051		606,179
Unrealized Losses 12 months or more	95,379		16,243
Total Fair Value	2,535,544		2,323,519
Total Unrealized Losses	184,603		41,644
Puerto Rico government obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Fair Value Less than 12 months	0		0
Unrealized Losses Less than 12 months	0		0
Fair Value 12 months or more	2,809		2,850
Unrealized Losses 12 months or more	246		416
Total Fair Value	2,809		2,850
Total Unrealized Losses	246		416
Allowance for credit losses	400		300
MBS [Member] | FHLMC [Member]
Schedule Of Available For Sale Securities [Line Items]
Fair Value Less than 12 months	779,727		986,345
Unrealized Losses Less than 12 months	83,109		16,144
Fair Value 12 months or more	441,983		221,896
Unrealized Losses 12 months or more	71,319		8,481
Total Fair Value	1,221,710		1,208,241
Total Unrealized Losses	154,428		24,625
MBS [Member] | GNMA [Member]
Schedule Of Available For Sale Securities [Line Items]
Fair Value Less than 12 months	184,481		194,271
Unrealized Losses Less than 12 months	12,334		1,329
Fair Value 12 months or more	57,306		41,233
Unrealized Losses 12 months or more	9,290		984
Total Fair Value	241,787		235,504
Total Unrealized Losses	21,624		2,313
MBS [Member] | FNMA [Member]
Schedule Of Available For Sale Securities [Line Items]
Fair Value Less than 12 months	1,004,966		1,237,701
Unrealized Losses Less than 12 months	89,854		19,843
Fair Value 12 months or more	508,377		112,559
Unrealized Losses 12 months or more	74,758		3,821
Total Fair Value	1,513,343		1,350,260
Total Unrealized Losses	164,612		23,664
MBS [Member] | Collateralized mortgage obligations guaranteed by FHLMC, FNMA and GNMA [Member]
Schedule Of Available For Sale Securities [Line Items]
Fair Value Less than 12 months	260,811		466,004
Unrealized Losses Less than 12 months	36,877		13,552
Fair Value 12 months or more	146,590		16,656
Unrealized Losses 12 months or more	25,216		360
Total Fair Value	407,401		482,660
Total Unrealized Losses	62,093		13,912
MBS [Member] | Private label [Member]
Schedule Of Available For Sale Securities [Line Items]
Fair Value Less than 12 months	0		0
Unrealized Losses Less than 12 months	0		0
Fair Value 12 months or more	6,371		7,234
Unrealized Losses 12 months or more	2,526		1,963
Total Fair Value	6,371		7,234
Total Unrealized Losses	$ 2,526		$ 1,963