Acquisitions - Schedule of Recognized Identifiable Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Feb. 01, 2022	Mar. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Liabilities assumed:
Goodwill		$ 1,137,600	$ 621,600	$ 621,600
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	181,900
Loans held for investment	7,713,400
Allowance for credit losses	(84,300)
Premises and equipment, including right of use lease assets	144,100
Other real estate owned (“OREO”)	15,800
Company owned life insurance	186,600
Core deposit intangibles	49,100
Customer relationship intangible	22,800
Mortgage servicing rights	1,300
Deferred tax assets, net	76,100
Other assets	198,000
Total assets acquired	13,311,800
Liabilities assumed:
Deposits	11,688,000
Securities sold under repurchase agreements	74,000
Accrued expenses and other liabilities	107,100
FHLB advances	122,900
Subordinated debt	36,400
Subordinated debentures held by subsidiary trusts	76,100
Total liabilities assumed	12,104,500
Net assets acquired	1,207,300
Class A common stock	1,723,300
Total consideration paid (1)	1,723,300
Goodwill	516,000
Cash paid in lieu of fractional shares	$ 13