Borrowings - Schedules of Short-term Borrowings and Long-term Borrowings (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Aug. 05, 2014
Long-Term Borrowings
Available capacity	$ 2,613,232	$ 752,509
Unamortized Deferred Issuance Costs	(113)	(206)
Long-term borrowings	69,887	69,794
Total borrowings, gross	1,395,690	1,080,101
Total borrowings	1,395,577	$ 1,079,895
Borrowings - Principal	2,300,000
Investment securities pledged with collateral par	269,900
Asset Pledged as Collateral
Long-Term Borrowings
Available capacity	$ 2,000,000
Subordinated notes, 5.75%
Long-Term Borrowings
Interest rate (as a percent)	5.75%	5.75%	5.75%
Long-term borrowings, gross	$ 70,000	$ 70,000
Unamortized Deferred Issuance Costs	(113)	(206)
Long-term borrowings	69,887	69,794
Secured Debt
Long-Term Borrowings
Short-term borrowings	1,300,001	975,001
Available capacity	2,613,232	752,509
Customer repurchase agreements
Long-Term Borrowings
Short-term borrowings	$ 25,689	$ 35,100
Interest rate (as a percent)	3.43%	2.94%
FHLB secured borrowings | Secured Debt
Long-Term Borrowings
Short-term borrowings	$ 0	$ 975,001
Available capacity	1,736,759	$ 145,104
Interest rate (as a percent)		4.57%
BTFP secured borrowings | Asset Pledged as Collateral
Long-Term Borrowings
Available capacity	253,100
BTFP secured borrowings | Secured Debt
Long-Term Borrowings
Short-term borrowings	1,300,001
Available capacity	$ 253,133
Interest rate (as a percent)	4.53%
Discount window secured borrowings | Secured Debt
Long-Term Borrowings
Available capacity	$ 606,178	$ 607,405
Raymond James repurchase agreement | Asset Pledged as Collateral
Long-Term Borrowings
Available capacity	17,200
Raymond James repurchase agreement | Secured Debt
Long-Term Borrowings
Available capacity	$ 17,162