Consolidated Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating activities
Net income	$ 33,547,000	$ 57,908,000
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Provision for credit losses on loans	1,500,000	0
Depreciation, amortization and accretion	12,804,000	10,059,000
Deferred income tax expense	4,649,000	5,542,000
Funding of mortgage loans held for sale	(595,046,000)	(1,143,349,000)
Proceeds from sales of mortgage loans held for sale	769,797,000	1,082,538,000
Gains on sales of mortgage loans held for sale	(6,047,000)	(33,901,000)
Valuation adjustment to mortgage servicing rights	0	(13,561,000)
Gains on sales of securities	0	(1,357,000)
Gains on sales of premises and equipment	(3,000)	(22,000)
Stock-based compensation expense	3,338,000	2,756,000
Increase (decrease) in other assets	5,746,000	(11,800,000)
Decrease in other liabilities	(24,469,000)	(11,601,000)
Net cash provided by (used in) operating activities	205,816,000	(56,788,000)
Investing activities
Purchases of securities available for sale	(285,635,000)	(465,245,000)
Proceeds from sales of securities available for sale	0	155,391,000
Proceeds from call/maturities of securities available for sale	128,155,000	95,382,000
Purchases of securities held to maturity	(79,434,000)	0
Proceeds from call/maturities of securities held to maturity	7,620,000	0
Net (increase) decrease in loans	(264,251,000)	243,250,000
Purchases of premises and equipment	(2,030,000)	(2,630,000)
Proceeds from sales of premises and equipment	100,000	34,000
Purchase of bank-owned life insurance	(80,000,000)	0
Net change in FHLB stock	(422,000)	(24,000)
Proceeds from sales of other assets	956,000	1,962,000
Net cash paid in acquisition of businesses	(10,066,000)	0
Other, net	207,000	1,346,000
Net cash (used in) provided by investing activities	(584,800,000)	29,466,000
Financing activities
Net (decrease) increase in noninterest-bearing deposits	(11,868,000)	450,312,000
Net increase in interest-bearing deposits	97,041,000	227,515,000
Net increase (decrease) in short-term borrowings	67,852,000	(9,186,000)
Repayment of long-term debt	(32,008,000)	(42,000)
Cash paid for dividends	(12,505,000)	(12,564,000)
Net cash provided by financing activities	108,512,000	656,035,000
Net (decrease) increase in cash and cash equivalents	(270,472,000)	628,713,000
Cash and cash equivalents at beginning of period	1,877,965,000	633,203,000
Cash and cash equivalents at end of period	1,607,493,000	1,261,916,000
Supplemental disclosures
Cash paid for interest	10,324,000	15,108,000
Cash paid for income taxes	6,195,000	18,032,000
Noncash transactions:
Transfers of loans to other real estate owned	200,000	2,039,000
Recognition of operating right-of-use assets	30,000	3,601,000
Recognition of operating lease liabilities	$ 30,000	$ 3,601,000