Securities Held-to-Maturity - Roll forward of Allowance (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)
Changes in the allowance for credit losses
Allowance for credit loss, beginning balance	$ 3,153
Provision for credit loss expense/(reversal)	3,103
Allowance for credit loss, ending balance	6,256
APL certificates
Changes in the allowance for credit losses
Allowance for credit loss, beginning balance	2,783
Provision for credit loss expense/(reversal)	(511)
Allowance for credit loss, ending balance	2,272
B Piece bonds
Changes in the allowance for credit losses
Allowance for credit loss, beginning balance	370
Provision for credit loss expense/(reversal)	3,614
Allowance for credit loss, ending balance	$ 3,984