FANNIE MAE COMMITMENTS AND PLEDGED SECURITIES - Agency Multifamily Mortgage Based Securities Pledged Securities (Detail) - Agency Mortgage Backed Securities - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Investments in Agency debt securities
Fair Value	$ 114,563	$ 106,862
Amortized cost	113,580	106,963
Total gains for securities with net gains in AOCI	1,145	77
Total losses for securities with net losses in AOCI	(162)	(178)
Maturities - Fair Value
After one year through five years	2,812
After five years through ten years	92,040
After ten years	19,711
Total	114,563	106,862
Maturities - Amortized Cost
After one year through five years	2,815
After five years through ten years	92,153
After ten years	18,612
Total	$ 113,580	$ 106,963