Investment Securities - Available For Sale with Unrealized Losses, Aggregated by Category and Period of Continuous Unrealized Loss (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Available for sale securities
Less than 12 months Fair Value	$ 777,000	$ 30,000
Less than 12 months Unrealized Losses	1,000	0
12 months or longer Fair Value	98,994,000	105,495,000
12 months or longer Unrealized Losses	8,587,000	8,710,000
Total Fair Value	99,771,000	105,525,000
Total Unrealized Losses	8,588,000	8,710,000
Portfolio layer method fair value hedge basis adjustments, excluded from unrealized losses on available for sale securities	47,000	19,000
U.S. agency mortgage-backed securities
Available for sale securities
Less than 12 months Fair Value	1,000	1,000
Less than 12 months Unrealized Losses	0	0
12 months or longer Fair Value	60,171,000	62,794,000
12 months or longer Unrealized Losses	6,402,000	6,378,000
Total Fair Value	60,172,000	62,795,000
Total Unrealized Losses	6,402,000	6,378,000
Less than 12 months unrealized losses less than stated amount	500	500
U.S. Treasury securities
Available for sale securities
Less than 12 months Fair Value	754,000	0
Less than 12 months Unrealized Losses	1,000	0
12 months or longer Fair Value	18,447,000	19,450,000
12 months or longer Unrealized Losses	901,000	989,000
Total Fair Value	19,201,000	19,450,000
Total Unrealized Losses	902,000	989,000
Corporate debt securities
Available for sale securities
Less than 12 months Fair Value	0	0
Less than 12 months Unrealized Losses	0	0
12 months or longer Fair Value	11,193,000	12,484,000
12 months or longer Unrealized Losses	864,000	860,000
Total Fair Value	11,193,000	12,484,000
Total Unrealized Losses	864,000	860,000
Asset-Backed Securities
Available for sale securities
Less than 12 months Fair Value	22,000	29,000
Less than 12 months Unrealized Losses	0	0
12 months or longer Fair Value	7,676,000	9,058,000
12 months or longer Unrealized Losses	319,000	378,000
Total Fair Value	7,698,000	9,087,000
Total Unrealized Losses	319,000	378,000
Less than 12 months unrealized losses less than stated amount	500	500
Foreign government agency securities
Available for sale securities
Less than 12 months Fair Value	0	0
Less than 12 months Unrealized Losses	0	0
12 months or longer Fair Value	803,000	1,002,000
12 months or longer Unrealized Losses	28,000	33,000
Total Fair Value	803,000	1,002,000
Total Unrealized Losses	28,000	33,000
U.S. state and municipal securities
Available for sale securities
Less than 12 months Fair Value	0	0
Less than 12 months Unrealized Losses	0	0
12 months or longer Fair Value	575,000	579,000
12 months or longer Unrealized Losses	57,000	55,000
Total Fair Value	575,000	579,000
Total Unrealized Losses	57,000	55,000
Non-agency commercial mortgage-backed securities
Available for sale securities
Less than 12 months Fair Value	0	0
Less than 12 months Unrealized Losses	0	0
12 months or longer Fair Value	110,000	109,000
12 months or longer Unrealized Losses	13,000	14,000
Total Fair Value	110,000	109,000
Total Unrealized Losses	13,000	14,000
Other
Available for sale securities
Less than 12 months Fair Value	0	0
Less than 12 months Unrealized Losses	0	0
12 months or longer Fair Value	19,000	19,000
12 months or longer Unrealized Losses	3,000	3,000
Total Fair Value	19,000	19,000
Total Unrealized Losses	$ 3,000	$ 3,000