Mergers and Acquisitions - Summary of Fair Value of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands		3 Months Ended	9 Months Ended
	Apr. 01, 2025	Sep. 30, 2025	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024	Dec. 31, 2023
Business Combination [Line Items]
Goodwill		$ 1,411,711	$ 1,411,711	$ 988,898	$ 988,898	$ 991,665
Business Combination, Recognized Asset Acquired to Liability Assumed, Excess (Less), and Goodwill [Abstract]
Goodwill			$ 422,813	$ 0
The First
Business Combination [Line Items]
Cash and cash equivalents	$ 263,352
Securities	1,528,975
Loans, including loans held for sale	5,327,056
Premises and equipment	174,770
Bank-owned life insurance	146,601
Other real estate owned	8,413
Core deposit intangible	56,899
Other assets	169,500
Total assets	7,675,566
Deposits	6,456,784
Borrowings	422,067
Other liabilities	75,760
Total liabilities	6,954,611
Net identifiable assets acquired over liabilities assumed	720,955
Goodwill	272,520
Net assets acquired over liabilities assumed	993,475
Business Combination, Recognized Asset Acquired to Liability Assumed, Excess (Less), and Goodwill [Abstract]
Goodwill		$ 8,071
The First | Preliminary Adjustments
Business Combination, Recognized Asset Acquired to Liability Assumed, Excess (Less), and Goodwill [Abstract]
Cash and cash equivalents	0
Securities	(71,772)
Loans, including loans held for sale	(152,153)
Premises and equipment	(1,596)
Bank-owned life insurance	0
Other real estate owned	2,696
Core deposit intangible	102,711
Other assets	3,859
Total assets	(116,255)
Deposits	(7,391)
Borrowings	(2,902)
Other liabilities	(15,903)
Total liabilities	(26,196)
Net identifiable assets acquired over liabilities assumed	(90,059)
Goodwill	158,364
Net assets acquired over liabilities assumed	68,305
The First | Measurement Period Adjustments
Business Combination, Recognized Asset Acquired to Liability Assumed, Excess (Less), and Goodwill [Abstract]
Cash and cash equivalents	0
Securities	174
Loans, including loans held for sale	(1,511)
Premises and equipment	0
Bank-owned life insurance	0
Other real estate owned	0
Core deposit intangible	0
Other assets	379
Total assets	(958)
Deposits	0
Borrowings	0
Other liabilities	61
Total liabilities	61
Net identifiable assets acquired over liabilities assumed	(1,019)
Goodwill	(8,071)
Net assets acquired over liabilities assumed	(9,090)
Fair Value of Net Assets Acquired at Date of Acquisition
Business Combination [Line Items]
Cash and cash equivalents	263,352
Securities	1,457,377
Loans, including loans held for sale	5,173,392
Premises and equipment	173,174
Bank-owned life insurance	146,601
Other real estate owned	11,109
Core deposit intangible	159,610
Other assets	173,738
Total assets	7,558,353
Deposits	6,449,393
Borrowings	419,165
Other liabilities	59,918
Total liabilities	6,928,476
Net identifiable assets acquired over liabilities assumed	629,877
Goodwill	422,813
Net assets acquired over liabilities assumed	$ 1,052,690