FANNIE MAE COMMITMENTS AND PLEDGED SECURITIES - Agency Multifamily Mortgage Based Securities Pledged Securities (Detail) - Agency Mortgage Backed Securities $ in Thousands	Jun. 30, 2020 USD ($) security	Dec. 31, 2019 USD ($)
Investments in Agency debt securities
Fair Value	$ 122,524	$ 114,563
Amortized cost	122,257	113,580
Total gains for securities with net gains in AOCI	600	1,145
Total losses for securities with net losses in AOCI	(333)	(162)
Fair value of securities with unrealized losses	$ 70,709	66,526
Pledged securities in a continuous unrealized loss position for more than 12 months | security	0
Maturities - Fair Value
After one year through five years	$ 2,485
After five years through ten years	99,673
After ten years	20,366
Total	122,524	114,563
Maturities - Amortized Cost
After one year through five years	2,508
After five years through ten years	99,820
After ten years	19,929
Total	$ 122,257	$ 113,580