Consolidated Statements of Cash Flows - USD ($)	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Operating Activities
Net income	$ 151,007,000	$ 66,293,000
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	6,098,000	88,108,000
Depreciation of premises, furniture, and equipment	11,149,000	12,540,000
Net amortization of premium on securities	15,465,000	16,203,000
Net securities gains	0	(13,323,000)
Gains on sales of 1-4 family mortgages and corporate loans held-for-sale	(22,205,000)	(14,091,000)
Net (gains) losses on sales and valuation adjustments of OREO	(141,000)	221,000
Amortization of the FDIC indemnification asset	0	892,000
Net (gains) losses on sales and valuation adjustments of premises, furniture, and equipment	(1,103,000)	9,033,000
BOLI income	(5,222,000)	(5,503,000)
Share-based compensation expense	11,539,000	11,242,000
Tax benefit related to share-based compensation	377,000	271,000
Amortization of other intangible assets	8,398,000	8,400,000
Originations of mortgage loans held-for-sale	(664,682,000)	(592,196,000)
Proceeds from sales of mortgage loans held-for-sale	713,775,000	551,105,000
Net increase in equity securities	(38,444,000)	(12,885,000)
Net decrease (increase) in accrued interest receivable and other assets	44,031,000	(111,925,000)
Net (decrease) increase in accrued interest payables and other liabilities	(7,508,000)	80,487,000
Net cash provided by operating activities	222,534,000	94,872,000
Investing Activities
Proceeds from maturities, repayments, and calls of securities available-for-sale	774,225,000	986,145,000
Proceeds from sales of securities available-for-sale	34,834,000	281,869,000
Purchases of securities available-for-sale	(1,006,329,000)	(1,499,176,000)
Proceeds from maturities, repayments, and calls of securities held-to-maturity	1,218,000	9,934,000
Purchases of securities held-to-maturity	0	(10,050,000)
Net sales (purchases) of FHLB stock	11,330,000	(22,711,000)
Net increase in loans	(74,022,000)	(1,078,458,000)
Premiums paid on BOLI, net of proceeds from claims	5,936,000	3,922,000
Proceeds from sales of OREO	3,288,000	3,709,000
Proceeds from sales of premises, furniture, and equipment	3,908,000	1,132,000
Purchases of premises, furniture, and equipment	(5,321,000)	(7,680,000)
Net cash received from acquisition	0	142,282,000
Net cash used in investing activities	(250,933,000)	(1,189,082,000)
Financing Activities
Net increase in deposit accounts	1,185,938,000	1,570,219,000
Net (decrease) increase in borrowed funds	(271,842,000)	286,890,000
Swap termination costs	0	(14,285,000)
Net proceeds from the issuance of preferred stock	0	221,047,000
Repurchases of common stock	(14,929,000)	(22,557,000)
Cash dividends paid	(60,088,000)	(52,522,000)
Restricted stock activity	(2,987,000)	(3,063,000)
Net cash provided by financing activities	836,092,000	1,985,729,000
Net increase in cash and cash equivalents	807,693,000	891,519,000
Cash and cash equivalents at beginning of period	1,117,244,000	299,221,000
Cash and cash equivalents at end of period	1,924,937,000	1,190,740,000
Supplemental Disclosures of Cash Flow Information:
Income taxes paid	41,507,000	40,012,000
Interest paid to depositors and creditors	31,134,000	65,198,000
Dividends declared, but unpaid	15,825,000	15,859,000
Stock issued for acquisitions, net of issuance costs	0	71,883,000
Non-cash transfers of loans to OREO	0	121,000
Non-cash transfers of loans held-for-investment to (from) loans held-for-sale	$ 14,875,000
Non-cash transfers of loans held-for-investment to (from) loans held-for-sale		$ (243,000)