Financial Derivatives - Schedule of Derivative Instruments in Statement of Financial Position (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Notional Disclosures [Abstract]
Notional Amount	$ 24,460,267	$ 23,878,611
Asset
Fair value, asset	28,855	37,409
Netting adjustments	(3,180)	(5,212)
(Liability)
Fair value, liability	(188,362)	(175,326)
Netting adjustments	3,180	5,212
Designated as hedge | Fair value hedges: | Receive fixed non-callable
Notional Disclosures [Abstract]
Notional Amount	8,942,935	8,149,871
Asset
Fair value, asset	2,996	13,689
(Liability)
Fair value, liability	$ (11)	$ (366)
Weighted- Average Pay Rate	5.46%	2.23%
Weighted- Average Receive Rate	2.74%	4.33%
Weighted- Average Remaining Term (in years)	1 year 8 months 1 day	10 years 9 months 3 days
Designated as hedge | Fair value hedges: | Pay fixed non-callable
Notional Disclosures [Abstract]
Notional Amount	$ 8,830,943	$ 10,033,750
Asset
Fair value, asset	81	19
(Liability)
Fair value, liability	$ (11,054)	$ (4,686)
Weighted- Average Pay Rate	2.39%	4.31%
Weighted- Average Receive Rate	5.33%	2.03%
Weighted- Average Remaining Term (in years)	9 years 10 months 20 days	1 year 7 months 20 days
Designated as hedge | Fair value hedges: | Receive fixed callable
Notional Disclosures [Abstract]
Notional Amount	$ 4,181,077	$ 2,764,577
Asset
Fair value, asset	0	461
(Liability)
Fair value, liability	$ (179,299)	$ (174,757)
Weighted- Average Pay Rate	5.26%	4.21%
Weighted- Average Receive Rate	3.06%	1.98%
Weighted- Average Remaining Term (in years)	2 years 4 months 13 days	3 years 2 months 4 days
Designated as hedge | Cash flow hedges: | Pay fixed non-callable
Notional Disclosures [Abstract]
Notional Amount	$ 563,000	$ 588,000
Asset
Fair value, asset	27,510	27,275
(Liability)
Fair value, liability	$ (372)	$ 0
Weighted- Average Pay Rate	1.94%	1.93%
Weighted- Average Receive Rate	5.74%	4.72%
Weighted- Average Remaining Term (in years)	4 years 6 months 3 days	5 years 18 days
No hedge designation | Receive fixed non-callable
Notional Disclosures [Abstract]
Notional Amount	$ 851,146	$ 287,750
Asset
Fair value, asset	69	0
(Liability)
Fair value, liability	$ (3)	$ (130)
Weighted- Average Pay Rate	5.34%	4.31%
Weighted- Average Receive Rate	4.51%	1.16%
Weighted- Average Remaining Term (in years)	8 months 12 days	1 year 9 months 3 days
No hedge designation | Pay fixed non-callable
Notional Disclosures [Abstract]
Notional Amount	$ 183,882	$ 187,479
Asset
Fair value, asset	1,240	1,065
(Liability)
Fair value, liability	$ (166)	$ (1)
Weighted- Average Pay Rate	2.92%	3.05%
Weighted- Average Receive Rate	5.44%	4.09%
Weighted- Average Remaining Term (in years)	4 years 3 days	4 years 6 months 7 days
No hedge designation | Basis swaps
Notional Disclosures [Abstract]
Notional Amount	$ 895,384	$ 1,860,384
Asset
Fair value, asset	58	112
(Liability)
Fair value, liability	$ (625)	$ (456)
Weighted- Average Pay Rate	5.43%	4.40%
Weighted- Average Receive Rate	5.45%	4.42%
Weighted- Average Remaining Term (in years)	3 years 10 months 20 days	2 years 5 months 15 days
No hedge designation | Treasury futures
Notional Disclosures [Abstract]
Notional Amount	$ 11,900	$ 6,800
Asset
Fair value, asset	81	0
Netting adjustments	(3,180)	(5,212)
(Liability)
Fair value, liability	(12)	(142)
Netting adjustments	$ 3,180	$ 5,212
Weighted- Average Forward Price (in dollars per share)	$ 108.64	$ 114.38