CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Assets
Cash and due from banks	$ 274,022	$ 246,716
Interest-bearing deposits in other banks	1,352,138	1,011,753
Investment securities, at fair value (amortized cost: $8,733,170 as of March 31, 2022 and $8,560,733 as of December 31, 2021)	8,062,384	8,428,032
Loans held for sale		538
Loans and leases	12,891,743	12,961,999
Less: allowance for credit losses	150,280	157,262
Net loans and leases	12,741,463	12,804,737
Premises and equipment, net	315,766	318,448
Other real estate owned and repossessed personal property		175
Accrued interest receivable	61,561	63,158
Bank-owned life insurance	471,401	471,819
Goodwill	995,492	995,492
Mortgage servicing rights	7,650	8,302
Other assets	760,843	643,240
Total assets	25,042,720	24,992,410
Deposits:
Interest-bearing	12,504,821	12,422,283
Noninterest-bearing	9,765,609	9,393,863
Total deposits	22,270,430	21,816,146
Retirement benefits payable	134,323	134,491
Other liabilities	352,818	384,861
Total liabilities	22,757,571	22,335,498
Commitments and contingent liabilities (Note 11)
Stockholders' equity
Common stock ($0.01 par value; authorized 300,000,000 shares; issued/outstanding: 140,875,595 / 127,686,307 as of March 31, 2022; issued/outstanding: 140,581,715 / 127,502,472 as of December 31, 2021)	1,409	1,406
Additional paid-in capital	2,530,795	2,527,663
Retained earnings	628,642	604,534
Accumulated other comprehensive loss, net	(517,502)	(121,693)
Treasury stock (13,189,288 shares as of March 31, 2022 and 13,079,243 shares as of December 31, 2021)	(358,195)	(354,998)
Total stockholders' equity	2,285,149	2,656,912
Total liabilities and stockholders' equity	$ 25,042,720	$ 24,992,410