Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
OPERATING ACTIVITIES
Net income	$ 173,152	$ 222,918
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Depreciation and amortization	36,660	35,396
Provision for credit losses	14,048	(31,396)
(Gain) loss on sale of investments	226	(15,846)
Net accretion of investment securities and assets	(32,531)	(36,929)
Net amortization on borrowings	274	404
Stock-based compensation expense	11,475	12,591
Gain on sale of premises and equipment, net of impairment	0	(591)
Gain on sale of foreclosed assets and other real estate owned	(424)	(76)
Gain on sale of mortgage loans held for sale	(7,187)	(29,222)
Gain on sale of loans	(282)	0
Gain on sale of branches	0	(5,316)
Deferred income taxes	2,924	3,585
Income from bank owned life insurance	(8,189)	(6,229)
Loss from early retirement of TruPS	365	0
Originations of mortgage loans held for sale	(436,477)	(752,480)
Proceeds from sale of mortgage loans held for sale	467,261	884,452
Changes in assets and liabilities:
Interest receivable	(5,852)	4,191
Other assets	(18,712)	(22,677)
Accrued interest and other liabilities	34,850	(41,674)
Income taxes payable	(5,373)	(1,199)
Net cash provided by operating activities	226,208	219,902
INVESTING ACTIVITIES
Net change in loans	(1,344,441)	2,056,058
Proceeds from sale of loans	51,856	26,472
Net change in due from banks - time	592	(201)
Purchases of premises and equipment, net	(25,757)	(36,832)
Proceeds from sale of premises and equipment	0	5,621
Proceeds from sale of foreclosed assets and other real estate owned	3,476	14,594
Proceeds from sale of available-for-sale securities	0	342,577
Proceeds from maturities of available-for-sale securities	974,625	559,259
Purchases of available-for-sale securities	(261,375)	(4,786,533)
Proceeds from maturities of held-to-maturity securities	60,215	13,804
Purchases of held-to-maturity securities	(329,660)	(694,734)
Purchases of bank owned life insurance death benefits	0	(160,000)
Proceeds from bank owned life insurance death benefits	1,873	3,814
Disposition of assets and liabilities held for sale	0	(134,166)
Purchase of Spirit of Texas Bancshares, Inc.	276,396	0
Net cash used in investing activities	(592,200)	(2,790,267)
FINANCING ACTIVITIES
Net change in deposits	63,128	1,075,422
Repayments of TruPS	(56,189)	0
Dividends paid on preferred stock	0	(39)
Dividends paid on common stock	(69,963)	(58,319)
Net change in other borrowed funds	(411,250)	(3,482)
Net change in federal funds purchased and securities sold under agreements to repurchase	(16,890)	(81,835)
Net shares issued (cancelled) under stock compensation plans	(4,105)	1,222
Shares issued under employee stock purchase plan	1,151	1,170
Repurchases of common stock	(111,133)	(54,513)
Net cash (used in) provided by financing activities	(605,251)	879,626
DECREASE IN CASH AND CASH EQUIVALENTS	(971,243)	(1,690,739)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	1,650,653	3,472,152
CASH AND CASH EQUIVALENTS, END OF PERIOD	$ 679,410	$ 1,781,413