Debt Securities - Debt Securities in an Unrealized Loss Position (Details) $ in Thousands	Sep. 30, 2022 USD ($) security	Dec. 31, 2021 USD ($) security
Available-for-sale
Number of available-for-sale securities | security	960	263
Less than 12 months, fair value	$ 2,474,402	$ 7,231,306
Less than 12 months, unrealized loss	(233,420)	(67,190)
12 months or more, fair value	3,067,879	187,060
12 months or more, unrealized loss	(425,474)	(5,501)
Total, fair value	5,542,281	7,418,366
Total, unrealized loss	$ (658,894)	$ (72,691)
U.S. government and federal agency
Available-for-sale
Number of available-for-sale securities | security	57	50
Less than 12 months, fair value	$ 293,319	$ 1,329,399
Less than 12 months, unrealized loss	(29,827)	(9,344)
12 months or more, fair value	144,052	5,457
12 months or more, unrealized loss	(14,988)	(252)
Total, fair value	437,371	1,334,856
Total, unrealized loss	$ (44,815)	$ (9,596)
U.S. government sponsored enterprises
Available-for-sale
Number of available-for-sale securities | security	15	11
Less than 12 months, fair value	$ 248,362	$ 239,928
Less than 12 months, unrealized loss	(25,938)	(996)
12 months or more, fair value	40,169	0
12 months or more, unrealized loss	(5,492)	0
Total, fair value	288,531	239,928
Total, unrealized loss	$ (31,430)	$ (996)
State and local governments
Available-for-sale
Number of available-for-sale securities | security	269	10
Less than 12 months, fair value	$ 277,582	$ 11,080
Less than 12 months, unrealized loss	(9,373)	(83)
12 months or more, fair value	10,984	1,760
12 months or more, unrealized loss	(1,901)	(40)
Total, fair value	288,566	12,840
Total, unrealized loss	$ (11,274)	$ (123)
Corporate bonds
Available-for-sale
Number of available-for-sale securities | security	17	3
Less than 12 months, fair value	$ 57,301	$ 12,483
Less than 12 months, unrealized loss	(1,141)	(17)
12 months or more, fair value	0	0
12 months or more, unrealized loss	0	0
Total, fair value	57,301	12,483
Total, unrealized loss	$ (1,141)	$ (17)
Residential mortgage-backed securities
Available-for-sale
Number of available-for-sale securities | security	446	151
Less than 12 months, fair value	$ 718,187	$ 5,335,632
Less than 12 months, unrealized loss	(91,231)	(53,434)
12 months or more, fair value	2,667,995	53,045
12 months or more, unrealized loss	(377,299)	(832)
Total, fair value	3,386,182	5,388,677
Total, unrealized loss	$ (468,530)	$ (54,266)
Commercial mortgage-backed securities
Available-for-sale
Number of available-for-sale securities | security	156	38
Less than 12 months, fair value	$ 879,651	$ 302,784
Less than 12 months, unrealized loss	(75,910)	(3,316)
12 months or more, fair value	204,679	126,798
12 months or more, unrealized loss	(25,794)	(4,377)
Total, fair value	1,084,330	429,582
Total, unrealized loss	$ (101,704)	$ (7,693)