Consolidated Statements of Cash Flows (Unaudited) - USD ($)	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Operating activities
Net income	$ 138,838,000	$ 52,130,000
Adjustments to reconcile net income to net cash provided by operating activities:
(Recovery of) provision for loan losses	(1,200,000)	76,350,000
Depreciation, amortization and accretion	34,421,000	22,727,000
Deferred income tax expense (benefit)	5,071,000	(8,494,000)
Funding of mortgage loans held for sale	(3,189,474,000)	(3,277,576,000)
Proceeds from sales of mortgage loans held for sale	3,230,039,000	3,310,402,000
Gains on sales of mortgage loans held for sale	(71,598,000)	(114,327,000)
Valuation adjustment to mortgage servicing rights	(13,561,000)	13,694,000
Gains on sales of securities	(2,121,000)	(31,000)
Penalty on prepayment of debt	0	118,000
(Gains) losses on sales of premises and equipment	(519,000)	35,000
Stock-based compensation expense	7,736,000	8,153,000
Increase in other assets	(16,429,000)	(87,405,000)
(Decrease) increase in other liabilities	(31,032,000)	48,269,000
Net cash provided by operating activities	90,171,000	44,045,000
Investing activities
Purchases of securities available for sale	(1,743,105,000)	(304,955,000)
Proceeds from sales of securities available for sale	176,406,000	8,773,000
Proceeds from call/maturities of securities available for sale	329,520,000	314,363,000
Net decrease (increase) in loans	917,343,000	(1,383,382,000)
Purchases of premises and equipment	(16,797,000)	(6,824,000)
Proceeds from sales of premises and equipment	8,715,000	0
Purchase of bank-owned life insurance	(50,000,000)	0
Net change in FHLB stock	(1,226,000)	10,607,000
Proceeds from sales of other assets	4,081,000	6,020,000
Other, net	2,803,000	0
Net cash used in investing activities	(372,260,000)	(1,355,398,000)
Financing activities
Net increase in noninterest-bearing deposits	807,602,000	1,206,472,000
Net increase in interest-bearing deposits	388,146,000	514,646,000
Net decrease in short-term borrowings	(10,087,000)	(446,467,000)
Proceeds from the issuance of long-term debt, net of issuance costs	0	98,299,000
Repayment of long-term debt	(1,742,000)	(246,000)
Cash paid for dividends	(37,578,000)	(37,607,000)
Repurchase of shares in connection with stock repurchase program	(21,314,000)	(24,569,000)
Net cash provided by financing activities	1,125,027,000	1,310,528,000
Net increase (decrease) in cash and cash equivalents	842,938,000	(825,000)
Cash and cash equivalents at beginning of period	633,203,000	414,930,000
Cash and cash equivalents at end of period	1,476,141,000	414,105,000
Supplemental disclosures
Cash paid for interest	37,827,000	61,351,000
Cash paid for income taxes	41,248,000	26,148,000
Noncash transactions:
Transfers of loans to other real estate owned	3,171,000	7,887,000
Financed sales of other real estate owned	442,000	151,000
Recognition of operating right-of-use assets	6,718,000	4,151,000
Recognition of operating lease liabilities	$ 6,718,000	$ 4,151,000