Investment Securities - Securities Held-to-Maturity (Details) - USD ($) $ in Thousands		Sep. 30, 2025		Dec. 31, 2024		Dec. 31, 2023
Investment Securities [Abstract]
Amortized cost		$ 734,628		$ 769,443
Gross unrecognized gains		1,128		46
Gross unrecognized losses		131,625		158,536
Fair value		604,131		610,953
Allowance for credit losses		450		450		$ 450
Mortgage-backed Securities [Member]
Investment Securities [Abstract]
Amortized cost	[1]	598,870		626,427
Gross unrecognized gains	[1]	57		0
Gross unrecognized losses	[1]	119,781		143,544
Fair value	[1]	479,146		482,883
Allowance for credit losses		0	[1]	0	[1]	0
Collateralized Mortgage Obligations [Member]
Investment Securities [Abstract]
Amortized cost	[1]	63,635		68,377
Gross unrecognized gains	[1]	0		0
Gross unrecognized losses	[1]	10,634		13,876
Fair value	[1]	53,001		54,501
Allowance for credit losses		0	[1]	0	[1]	0
Municipal Securities [Member]
Investment Securities [Abstract]
Amortized cost		72,123		74,639
Gross unrecognized gains		1,071		46
Gross unrecognized losses		1,210		1,116
Fair value		71,984		73,569
Allowance for credit losses		$ 450		$ 450		$ 450

[1] All mortgage-backed securities and collateralized mortgage obligations were issued by an agency or government sponsored entity of the U.S. Government.