FANNIE MAE COMMITMENTS AND PLEDGED SECURITIES - Agency Multifamily Mortgage Based Securities Pledged Securities (Detail) - Agency Mortgage Backed Securities - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Investments in Agency debt securities
Fair Value	$ 130,951	$ 142,624
Amortized Cost	133,421	144,801
Total gains for securities with net gains in AOCI	381	797
Total losses for securities with net losses in AOCI	(2,851)	(2,974)
Fair value of securities with unrealized losses	115,337	118,565
Maturities - Fair Value
After one year through five years	18,045
After five years through ten years	92,267
After ten years	20,639
Total	130,951	142,624
Maturities - Amortized Cost
After one year through five years	18,132
After five years through ten years	93,322
After ten years	21,967
Total	$ 133,421	$ 144,801