LOANS HELD FOR INVESTMENT - Corporation's Nonaccrual Status and Loans 90 Days or More Still Accruing (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable Modifications [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 11,060,658	$ 11,777,289
Financing Receivable, 90 Days or More Past Due, Still Accruing	114,679	145,095
PR And VI [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable, before Allowance for Credit Loss	9,113,918	9,788,106
Financing Receivable, 90 Days or More Past Due, Still Accruing	114,497	144,845
U S [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,946,740	1,989,183
Financing Receivable, 90 Days or More Past Due, Still Accruing	182	250
Portion Of Such Loans Contractually Past Due 90 Or More [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable, 90 Days or More Past Due, Still Accruing	20,600	26,300
Portion Of Such Loans Contractually Past Due 90 Or More [Member] | Conventional Residential Mortgage Loans [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable, 90 Days or More Past Due, Still Accruing	19,100	24,700
Portion Of Such Loans Contractually Past Due 90 Or More [Member] | Commercial Mortgage Loans [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable, 90 Days or More Past Due, Still Accruing	1,500	1,600
Portion Of Such Loans Contractually Past Due 90 Or More [Member] | PR And VI [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable, 90 Days or More Past Due, Still Accruing	20,600	26,300
Portion Of Such Loans Contractually Past Due 90 Or More [Member] | PR And VI [Member] | Conventional Residential Mortgage Loans [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable, 90 Days or More Past Due, Still Accruing	19,100	24,700
Portion Of Such Loans Contractually Past Due 90 Or More [Member] | PR And VI [Member] | Commercial Mortgage Loans [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable, 90 Days or More Past Due, Still Accruing	1,500	1,600
Residential Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,978,895	3,521,954
Financing Receivable, Purchase		800	$ 18,800
Residential Portfolio Segment [Member] | PR And VI [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,549,573	3,002,203
Residential Portfolio Segment [Member] | U S [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable, before Allowance for Credit Loss	429,322	519,751
Residential Portfolio Segment [Member] | GNMA [Member] | Repurchase Option Program [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable, before Allowance for Credit Loss	7,200	10,700
Financing Receivable, 90 Days or More Past Due, Still Accruing	7,200	10,700
Financing Receivable, Purchase	1,100	55,000	$ 33,500
Residential Portfolio Segment [Member] | GNMA [Member] | Repurchase Option Program [Member] | PR And VI [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable, 90 Days or More Past Due, Still Accruing	7,200	10,700
Financing Receivable, Purchase	1,100	55,000
PCD loans [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable, before Allowance for Credit Loss	117,500	130,900
PCD loans [Member] | PR And VI [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable, before Allowance for Credit Loss	117,500	130,900
Accrual Status [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring	363,400	393,300
Accrual Status [Member] | PR And VI [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring	357,700	386,700
Accrual Status [Member] | U S [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring	5,700	6,600
Accrual Status [Member] | Residential Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,923,768	3,396,587
Accrual Status [Member] | Residential Portfolio Segment [Member] | PR And VI [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,501,598	2,891,258
Accrual Status [Member] | Residential Portfolio Segment [Member] | U S [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 422,170	$ 505,329