Goodwill and Other Intangible Assets - Changes in Goodwill and Other Intangibles (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Jun. 30, 2022	Dec. 31, 2022
Finite-lived Intangible Assets [Roll Forward]
Core deposit premiums, beginning of period	$ 128,951
Amortization	(4,096)	$ (3,486)
Core deposit premiums, end of period	124,854			$ 128,951
Spirit of Texas Bancshares, Inc.
Finite-lived Intangible Assets [Roll Forward]
Core deposit premiums, beginning of period	36,500
Core deposit premiums, end of period				36,500
Core Deposit Premium
Finite-lived Intangible Assets [Roll Forward]
Core deposit premiums, beginning of period	116,016	93,862	$ 93,862	93,862
Acquisitions	0		36,500
Amortization	(3,689)		(14,346)
Core deposit premiums, end of period	112,327			116,016
Books of Business Intangible
Finite-lived Intangible Assets [Roll Forward]
Core deposit premiums, beginning of period	12,935	$ 12,373	12,373	12,373
Acquisitions	0		2,131	2,100
Amortization	(408)		$ (1,569)
Core deposit premiums, end of period	$ 12,527			$ 12,935