Debt Securities - Unrealized Loss Position (Details) $ in Thousands	Dec. 31, 2022 USD ($) security	Dec. 31, 2021 USD ($) security
Debt Securities
Number of securities | security	794	263
Less than 12 months, fair value	$ 1,075,458	$ 7,231,306
Less than 12 months, unrealized loss	(69,730)	(67,190)
12 months or more, fair value	4,144,180	187,060
12 months or longer, unrealized loss	(554,151)	(5,501)
Total, fair value	5,219,638	7,418,366
Total, unrealized loss	$ (623,881)	$ (72,691)
U.S. government and federal agency
Debt Securities
Number of securities | security	56	50
Less than 12 months, fair value	$ 4,150	$ 1,329,399
Less than 12 months, unrealized loss	(64)	(9,344)
12 months or more, fair value	435,375	5,457
12 months or longer, unrealized loss	(42,552)	(252)
Total, fair value	439,525	1,334,856
Total, unrealized loss	$ (42,616)	$ (9,596)
U.S. government sponsored enterprises
Debt Securities
Number of securities | security	14	11
Less than 12 months, fair value	$ 0	$ 239,928
Less than 12 months, unrealized loss	0	(996)
12 months or more, fair value	287,364	0
12 months or longer, unrealized loss	(32,793)	0
Total, fair value	287,364	239,928
Total, unrealized loss	$ (32,793)	$ (996)
State and local governments
Debt Securities
Number of securities | security	121	10
Less than 12 months, fair value	$ 71,512	$ 11,080
Less than 12 months, unrealized loss	(2,109)	(83)
12 months or more, fair value	20,753	1,760
12 months or longer, unrealized loss	(2,640)	(40)
Total, fair value	92,265	12,840
Total, unrealized loss	$ (4,749)	$ (123)
Corporate bonds
Debt Securities
Number of securities | security	5	3
Less than 12 months, fair value	$ 25,146	$ 12,483
Less than 12 months, unrealized loss	(992)	(17)
12 months or more, fair value	0	0
12 months or longer, unrealized loss	0	0
Total, fair value	25,146	12,483
Total, unrealized loss	$ (992)	$ (17)
Residential mortgage-backed securities
Debt Securities
Number of securities | security	441	151
Less than 12 months, fair value	$ 301,548	$ 5,335,632
Less than 12 months, unrealized loss	(24,581)	(53,434)
12 months or more, fair value	2,965,512	53,045
12 months or longer, unrealized loss	(414,511)	(832)
Total, fair value	3,267,060	5,388,677
Total, unrealized loss	$ (439,092)	$ (54,266)
Commercial mortgage-backed securities
Debt Securities
Number of securities | security	157	38
Less than 12 months, fair value	$ 673,102	$ 302,784
Less than 12 months, unrealized loss	(41,984)	(3,316)
12 months or more, fair value	435,176	126,798
12 months or longer, unrealized loss	(61,655)	(4,377)
Total, fair value	1,108,278	429,582
Total, unrealized loss	$ (103,639)	$ (7,693)