Acquisitions - Schedule of Recognized Identifiable Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Feb. 01, 2022	Jun. 30, 2023	Dec. 31, 2022
Liabilities assumed:
Goodwill		$ 1,100,900	$ 1,100,900
Great Western Bank
Assets acquired:
Cash and cash equivalents	$ 2,006,900
Investment securities	2,699,000
Securities purchased under agreement to resell	101,100
Loans held for sale	217,000
Loans held for investment	7,705,000
Allowance for credit losses	(59,500)
Premises and equipment, including right of use lease assets	144,700
Other real estate owned	15,800
Company-owned life insurance	186,600
Core deposit intangibles	50,100
Customer relationship intangible	22,800
Mortgage servicing rights	1,300
Deferred tax assets, net	60,200
Other assets	200,800
Total assets acquired	13,351,800
Liabilities assumed:
Deposits	11,688,000
Securities sold under repurchase agreements	74,000
Accrued expenses and other liabilities	110,400
FHLB advances	122,900
Subordinated debt	36,400
Subordinated debentures held by subsidiary trusts	76,100
Total liabilities assumed	12,107,800
Net assets acquired	1,244,000
Class A common stock	1,723,300
Total consideration paid (1)	1,723,300
Goodwill	479,300
Cash paid in lieu of fractional shares	$ 13