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LOANS HELD FOR INVESTMENT, NET - Credit Quality Indicators (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020 | Dec. 31, 2020
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Percentage of aggregate rental income |  |  | 50.00% |  |
Loans | $ 9,284,871 |  | $ 9,284,871 |  | $ 5,622,044
2021 | 1,329,531 |  | 1,329,531 |  |
2020 | 1,608,571 |  | 1,608,571 |  |
2019 | 1,354,530 |  | 1,354,530 |  |
2018 | 780,886 |  | 780,886 |  |
2017 | 954,652 |  | 954,652 |  |
2016 and Prior | 2,577,987 |  | 2,577,987 |  |
Revolving | 619,704 |  | 619,704 |  |
Revolving-Term | 38,297 |  | 38,297 |  |
Total Loans | 9,264,158 |  | 9,264,158 |  |
Pass |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2021 | 1,321,842 |  | 1,321,842 |  |
2020 | 1,582,785 |  | 1,582,785 |  |
2019 | 1,279,298 |  | 1,279,298 |  |
2018 | 684,132 |  | 684,132 |  |
2017 | 842,155 |  | 842,155 |  |
2016 and Prior | 2,363,465 |  | 2,363,465 |  |
Revolving | 578,714 |  | 578,714 |  |
Revolving-Term | 28,110 |  | 28,110 |  |
Total Loans | 8,680,501 |  | 8,680,501 |  |
Special Mention |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2021 | 5,354 |  | 5,354 |  |
2020 | 16,624 |  | 16,624 |  |
2019 | 15,153 |  | 15,153 |  |
2018 | 8,285 |  | 8,285 |  |
2017 | 23,907 |  | 23,907 |  |
2016 and Prior | 40,023 |  | 40,023 |  |
Revolving | 2,531 |  | 2,531 |  |
Revolving-Term | 2,457 |  | 2,457 |  |
Total Loans | 114,334 |  | 114,334 |  |
Substandard |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2021 | 2,335 |  | 2,335 |  |
2020 | 9,162 |  | 9,162 |  |
2019 | 49,886 |  | 49,886 |  |
2018 | 87,694 |  | 87,694 |  |
2017 | 76,601 |  | 76,601 |  |
2016 and Prior | 174,469 |  | 174,469 |  |
Revolving | 38,459 |  | 38,459 |  |
Revolving-Term | 7,730 |  | 7,730 |  |
Total Loans | 446,336 |  | 446,336 |  |
Doubtful |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2019 | 10,193 |  | 10,193 |  |
2018 | 775 |  | 775 |  |
2017 | 11,989 |  | 11,989 |  |
2016 and Prior | 30 |  | 30 |  |
Total Loans | 22,987 |  | 22,987 |  |
Criticized |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Sold amount | 11,900 | $ 3,000 | 66,500 | $ 10,000 |
Total real estate loans |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans | 8,251,743 |  | 8,251,743 |  | 4,978,195
Total real estate loans | Pass |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 4,681,059
Total real estate loans | Special Mention |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 83,761
Total real estate loans | Substandard |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 213,375
Total real estate loans | Doubtful |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 0
One-to-four family residential and cooperative/condominium apartment |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans | 683,665 |  | 683,665 |  | 184,989
2021 | 104,830 |  | 104,830 |  |
2020 | 94,776 |  | 94,776 |  |
2019 | 88,599 |  | 88,599 |  |
2018 | 81,622 |  | 81,622 |  |
2017 | 86,626 |  | 86,626 |  |
2016 and Prior | 160,666 |  | 160,666 |  |
Revolving | 53,329 |  | 53,329 |  |
Revolving-Term | 13,217 |  | 13,217 |  |
Total Loans | 683,665 |  | 683,665 |  |
One-to-four family residential and cooperative/condominium apartment | Pass |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 183,293
2021 | 104,830 |  | 104,830 |  |
2020 | 93,315 |  | 93,315 |  |
2019 | 86,214 |  | 86,214 |  |
2018 | 79,981 |  | 79,981 |  |
2017 | 84,075 |  | 84,075 |  |
2016 and Prior | 143,807 |  | 143,807 |  |
Revolving | 52,483 |  | 52,483 |  |
Revolving-Term | 11,162 |  | 11,162 |  |
Total Loans | 655,867 |  | 655,867 |  |
One-to-four family residential and cooperative/condominium apartment | Special Mention |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 0
2019 | 337 |  | 337 |  |
2018 | 756 |  | 756 |  |
2017 | 345 |  | 345 |  |
2016 and Prior | 2,168 |  | 2,168 |  |
Revolving | 846 |  | 846 |  |
Revolving-Term | 1,089 |  | 1,089 |  |
Total Loans | 5,541 |  | 5,541 |  |
One-to-four family residential and cooperative/condominium apartment | Substandard |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 1,696
2020 | 1,461 |  | 1,461 |  |
2019 | 2,048 |  | 2,048 |  |
2018 | 862 |  | 862 |  |
2017 | 2,206 |  | 2,206 |  |
2016 and Prior | 14,691 |  | 14,691 |  |
Revolving-Term | 966 |  | 966 |  |
Total Loans | 22,234 |  | 22,234 |  |
One-to-four family residential and cooperative/condominium apartment | Doubtful |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 0
2018 | 23 |  | 23 |  |
Total Loans | 23 |  | 23 |  |
Multifamily residential and residential mixed-use |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans | 3,468,262 |  | 3,468,262 |  | 2,758,743
2021 | 426,164 |  | 426,164 |  |
2020 | 360,450 |  | 360,450 |  |
2019 | 543,514 |  | 543,514 |  |
2018 | 221,003 |  | 221,003 |  |
2017 | 437,487 |  | 437,487 |  |
2016 and Prior | 1,470,245 |  | 1,470,245 |  |
Revolving | 8,574 |  | 8,574 |  |
Revolving-Term | 825 |  | 825 |  |
Total Loans | 3,468,262 |  | 3,468,262 |  |
Multifamily residential and residential mixed-use | Pass |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 2,523,258
2021 | 426,164 |  | 426,164 |  |
2020 | 347,900 |  | 347,900 |  |
2019 | 493,077 |  | 493,077 |  |
2018 | 193,738 |  | 193,738 |  |
2017 | 373,965 |  | 373,965 |  |
2016 and Prior | 1,329,688 |  | 1,329,688 |  |
Revolving | 5,111 |  | 5,111 |  |
Revolving-Term | 825 |  | 825 |  |
Total Loans | 3,170,468 |  | 3,170,468 |  |
Multifamily residential and residential mixed-use | Special Mention |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 56,400
2020 | 12,550 |  | 12,550 |  |
2019 | 14,551 |  | 14,551 |  |
2017 | 11,842 |  | 11,842 |  |
2016 and Prior | 22,378 |  | 22,378 |  |
Total Loans | 61,321 |  | 61,321 |  |
Multifamily residential and residential mixed-use | Substandard |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 179,085
2019 | 35,886 |  | 35,886 |  |
2018 | 27,265 |  | 27,265 |  |
2017 | 51,680 |  | 51,680 |  |
2016 and Prior | 118,179 |  | 118,179 |  |
Revolving | 3,463 |  | 3,463 |  |
Total Loans | 236,473 |  | 236,473 |  |
Multifamily residential and residential mixed-use | Doubtful |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 0
Commercial real estate ("CRE") |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans | 3,814,437 |  | 3,814,437 |  | 1,878,167
2021 | 643,923 |  | 643,923 |  |
2020 | 876,483 |  | 876,483 |  |
2019 | 585,974 |  | 585,974 |  |
2018 | 375,719 |  | 375,719 |  |
2017 | 368,772 |  | 368,772 |  |
2016 and Prior | 919,079 |  | 919,079 |  |
Revolving | 39,323 |  | 39,323 |  |
Revolving-Term | 5,164 |  | 5,164 |  |
Total Loans | 3,814,437 |  | 3,814,437 |  |
Commercial real estate ("CRE") | Pass |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 1,831,712
2021 | 636,234 |  | 636,234 |  |
2020 | 872,347 |  | 872,347 |  |
2019 | 578,758 |  | 578,758 |  |
2018 | 331,636 |  | 331,636 |  |
2017 | 337,930 |  | 337,930 |  |
2016 and Prior | 863,215 |  | 863,215 |  |
Revolving | 39,323 |  | 39,323 |  |
Revolving-Term | 5,164 |  | 5,164 |  |
Total Loans | 3,664,607 |  | 3,664,607 |  |
Commercial real estate ("CRE") | Special Mention |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 13,861
2021 | 5,354 |  | 5,354 |  |
2020 | 2,384 |  | 2,384 |  |
2018 | 4,191 |  | 4,191 |  |
2017 | 11,109 |  | 11,109 |  |
2016 and Prior | 15,416 |  | 15,416 |  |
Total Loans | 38,454 |  | 38,454 |  |
Commercial real estate ("CRE") | Substandard |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 32,594
2021 | 2,335 |  | 2,335 |  |
2020 | 1,752 |  | 1,752 |  |
2019 | 7,110 |  | 7,110 |  |
2018 | 39,892 |  | 39,892 |  |
2017 | 19,733 |  | 19,733 |  |
2016 and Prior | 40,448 |  | 40,448 |  |
Total Loans | 111,270 |  | 111,270 |  |
Commercial real estate ("CRE") | Doubtful |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 0
2019 | 106 |  | 106 |  |
Total Loans | 106 |  | 106 |  |
Acquisition, development, and construction ("ADC") |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans | 285,379 |  | 285,379 |  | 156,296
2021 | 101,947 |  | 101,947 |  |
2020 | 69,546 |  | 69,546 |  |
2019 | 62,414 |  | 62,414 |  |
2018 | 39,165 |  | 39,165 |  |
2017 | 8,120 |  | 8,120 |  |
2016 and Prior | 901 |  | 901 |  |
Revolving | 2,686 |  | 2,686 |  |
Revolving-Term | 600 |  | 600 |  |
Total Loans | 285,379 |  | 285,379 |  |
Acquisition, development, and construction ("ADC") | Pass |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 142,796
2021 | 101,947 |  | 101,947 |  |
2020 | 69,546 |  | 69,546 |  |
2019 | 62,414 |  | 62,414 |  |
2018 | 24,587 |  | 24,587 |  |
2017 | 8,120 |  | 8,120 |  |
2016 and Prior | 807 |  | 807 |  |
Revolving | 2,686 |  | 2,686 |  |
Revolving-Term | 600 |  | 600 |  |
Total Loans | 270,707 |  | 270,707 |  |
Acquisition, development, and construction ("ADC") | Special Mention |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 13,500
2018 | 1,078 |  | 1,078 |  |
Total Loans | 1,078 |  | 1,078 |  |
Acquisition, development, and construction ("ADC") | Substandard |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 0
2018 | 13,500 |  | 13,500 |  |
2016 and Prior | 94 |  | 94 |  |
Total Loans | 13,594 |  | 13,594 |  |
Acquisition, development, and construction ("ADC") | Doubtful |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 0
Commercial and Industrial ("C&I") Loans |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans | 1,012,415 |  | 1,012,415 |  | 641,533
2021 | 52,667 |  | 52,667 |  |
2020 | 207,316 |  | 207,316 |  |
2019 | 74,029 |  | 74,029 |  |
2018 | 63,377 |  | 63,377 |  |
2017 | 53,647 |  | 53,647 |  |
2016 and Prior | 27,096 |  | 27,096 |  |
Revolving | 515,792 |  | 515,792 |  |
Revolving-Term | 18,491 |  | 18,491 |  |
Total Loans | 1,012,415 |  | 1,012,415 |  |
Commercial and Industrial ("C&I") Loans | Pass |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 613,691
2021 | 52,667 |  | 52,667 |  |
2020 | 199,677 |  | 199,677 |  |
2019 | 58,835 |  | 58,835 |  |
2018 | 54,190 |  | 54,190 |  |
2017 | 38,065 |  | 38,065 |  |
2016 and Prior | 25,948 |  | 25,948 |  |
Revolving | 479,111 |  | 479,111 |  |
Revolving-Term | 10,359 |  | 10,359 |  |
Total Loans | 918,852 |  | 918,852 |  |
Commercial and Industrial ("C&I") Loans | Special Mention |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 2,131
2020 | 1,690 |  | 1,690 |  |
2019 | 265 |  | 265 |  |
2018 | 2,260 |  | 2,260 |  |
2017 | 611 |  | 611 |  |
2016 and Prior | 61 |  | 61 |  |
Revolving | 1,685 |  | 1,685 |  |
Revolving-Term | 1,368 |  | 1,368 |  |
Total Loans | 7,940 |  | 7,940 |  |
Commercial and Industrial ("C&I") Loans | Substandard |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 13,315
2020 | 5,949 |  | 5,949 |  |
2019 | 4,842 |  | 4,842 |  |
2018 | 6,175 |  | 6,175 |  |
2017 | 2,982 |  | 2,982 |  |
2016 and Prior | 1,057 |  | 1,057 |  |
Revolving | 34,996 |  | 34,996 |  |
Revolving-Term | 6,764 |  | 6,764 |  |
Total Loans | 62,765 |  | 62,765 |  |
Commercial and Industrial ("C&I") Loans | Doubtful |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 12,396
2019 | 10,087 |  | 10,087 |  |
2018 | 752 |  | 752 |  |
2017 | 11,989 |  | 11,989 |  |
2016 and Prior | 30 |  | 30 |  |
Total Loans | 22,858 |  | 22,858 |  |
Commercial and Industrial ("C&I") Loans | Total real estate loans |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 5,619,728
Commercial and Industrial ("C&I") Loans | Total real estate loans | Pass |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 5,294,750
Commercial and Industrial ("C&I") Loans | Total real estate loans | Special Mention |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 85,892
Commercial and Industrial ("C&I") Loans | Total real estate loans | Substandard |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 226,690
Commercial and Industrial ("C&I") Loans | Total real estate loans | Doubtful |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 12,396
Other Loans |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans | 20,713 |  | 20,713 |  | 2,316
Other Loans | Credit Risk Profile |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans | 20,713 |  | 20,713 |  |
Other Loans | Performing |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | 2,315
Other Loans | Performing | Credit Risk Profile |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans | 20,339 |  | 20,339 |  |
Other Loans | Non-Accrual |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans |  |  |  |  | $ 1
Other Loans | Non-Accrual | Credit Risk Profile |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Loans | $ 374 |  | $ 374 |  |

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