Business Combinations - Schedule of Fair Value of Consideration Transferred, Identifiable Net Assets Acquired and Resulting Goodwill (Detail) - USD ($) $ in Thousands			9 Months Ended
	Dec. 31, 2022	Mar. 25, 2022	Dec. 31, 2022	Dec. 31, 2021
Liabilities assumed:
Goodwill recognized	$ 304,442		$ 304,442	$ 220,872
Valley Republic Bancorp
Business Combination, Consideration Transferred [Abstract]
Fair value of shares issued	173,585	$ 173,585
Fair value of shares issued, Adjustments			0
Cash consideration	431	431
Cash consideration, Adjustments			0
Total fair value of consideration transferred	174,016	174,016
Total fair value of consideration transferred, Adjustments			0
Assets acquired:
Cash and cash equivalents	427,314	427,314	427,314
Cash and cash equivalents, Adjustments			0
Securities available for sale	109,716	109,716	109,716
Securities available for sale, Adjustments			0
Loans and leases	771,353	771,353	771,353
Loans and leases, Adjustments			0
Premises and equipment	4,658	4,658	4,658
Premises and equipment, Adjustments			0
Cash value of life insurance	13,609	13,609	13,609
Cash value of life insurance, Adjustments			0
Core deposit intangible	10,635	10,635	10,635
Core deposit intangible, Adjustments			0
Other assets	29,744	26,244	29,744
Other assets, Adjustments			3,500
Total assets acquired	1,367,029	1,363,529	1,367,029
Total assets acquired, Adjustments			3,500
Liabilities assumed:
Deposits	(1,215,479)	(1,215,479)	(1,215,479)
Deposits, Adjustments			0
Subordinated debt	(47,236)	(47,236)	(47,236)
Subordinated Debt, Adjustments			0
SERP liability	(3,352)	(3,352)	(3,352)
SERP liability, Adjustments			0
Other liabilities	(10,516)	(10,516)	(10,516)
Other liabilities, Adjustments			0
Total liabilities assumed	(1,276,583)	(1,276,583)	(1,276,583)
Total liabilities assumed, Adjustments			0
Total net assets acquired	90,446	86,946	90,446
Total net assets acquired, Adjustments			0
Goodwill recognized	$ 83,570	$ 87,070	83,570
Goodwill recognized, Adjustments			$ (3,500)