Organization, Basis of Presentation and Recently Adopted Accounting Standards - Schedule Of New Accounting Pronouncements And Changes In Accounting Principles (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Allowance for loan and lease losses	$ 162,244	$ 147,638	$ 156,636	$ 159,820
Other loans [Member]
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Allowance for loan and lease losses	20,930	$ 24,943	$ 27,870	$ 28,837
Previously Reported
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded	0
Allowance for loan and lease losses	147,638
Off-Balance Sheet, Credit Loss, Liability	461
Previously Reported | Multi Family
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Allowance for loan and lease losses	96,751
Previously Reported | Commercial Real Estate
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Allowance for loan and lease losses	20,744
Previously Reported | One to Four Family Mortgage Loans
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Allowance for loan and lease losses	1,051
Previously Reported | Acquisition, Development, and Construction Mortgage Loans
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Allowance for loan and lease losses	4,148
Previously Reported | Commercial and Industrial
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Allowance for loan and lease losses	24,819
Previously Reported | Other loans [Member]
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Allowance for loan and lease losses	125
Previously Reported | Collateralized Mortgage Backed Securities
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded	0
Previously Reported | Debt Securities [Member]
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded	0
Accounting Standards Update 2016-13 [Member]
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded	0
Allowance for loan and lease losses	149,549
Off-Balance Sheet, Credit Loss, Liability	12,990
Accounting Standards Update 2016-13 [Member] | Multi Family
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Allowance for loan and lease losses	104,918
Accounting Standards Update 2016-13 [Member] | Commercial Real Estate
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Allowance for loan and lease losses	12,543
Accounting Standards Update 2016-13 [Member] | One to Four Family Mortgage Loans
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Allowance for loan and lease losses	1,655
Accounting Standards Update 2016-13 [Member] | Acquisition, Development, and Construction Mortgage Loans
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Allowance for loan and lease losses	3,678
Accounting Standards Update 2016-13 [Member] | Commercial and Industrial
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Allowance for loan and lease losses	26,613
Accounting Standards Update 2016-13 [Member] | Other loans [Member]
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Allowance for loan and lease losses	142
Accounting Standards Update 2016-13 [Member] | Collateralized Mortgage Backed Securities
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded	0
Accounting Standards Update 2016-13 [Member] | Debt Securities [Member]
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded	0
Accounting Standards Update 2016-13 [Member] | Restatement Adjustment
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded	0
Allowance for loan and lease losses	1,911
Off-Balance Sheet, Credit Loss, Liability	12,529
Decrease in retained earnings, before tax	14,440
Accounting Standards Update 2016-13 [Member] | Restatement Adjustment | Multi Family
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Allowance for loan and lease losses	8,167
Accounting Standards Update 2016-13 [Member] | Restatement Adjustment | Commercial Real Estate
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Allowance for loan and lease losses	(8,201)
Accounting Standards Update 2016-13 [Member] | Restatement Adjustment | One to Four Family Mortgage Loans
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Allowance for loan and lease losses	604
Accounting Standards Update 2016-13 [Member] | Restatement Adjustment | Acquisition, Development, and Construction Mortgage Loans
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Allowance for loan and lease losses	(470)
Accounting Standards Update 2016-13 [Member] | Restatement Adjustment | Commercial and Industrial
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Allowance for loan and lease losses	1,794
Accounting Standards Update 2016-13 [Member] | Restatement Adjustment | Other loans [Member]
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Allowance for loan and lease losses	17
Accounting Standards Update 2016-13 [Member] | Restatement Adjustment | Collateralized Mortgage Backed Securities
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded	0
Accounting Standards Update 2016-13 [Member] | Restatement Adjustment | Debt Securities [Member]
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded	$ 0