Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
OPERATING ACTIVITIES
Net income	$ 92,549	$ 142,344
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Depreciation and amortization	24,230	23,837
Provision for credit losses	13,945	(11,506)
(Gain) loss on sale of investments	204	(10,598)
Net accretion of investment securities and assets	(24,494)	(24,377)
Net amortization on borrowings	192	269
Stock-based compensation expense	8,164	7,592
Gain on sale of premises and equipment, net of impairment	0	(606)
Gain on sale of foreclosed assets and other real estate owned	(290)	(177)
Gain on sale of mortgage loans held for sale	(4,333)	(20,006)
Gain on sale of loans	(228)	0
Gain on sale of branches	0	(5,300)
Deferred income taxes	917	6,315
Income from bank owned life insurance	(5,269)	(3,630)
Originations of mortgage loans held for sale	(329,833)	(534,124)
Proceeds from sale of mortgage loans held for sale	356,085	655,497
Changes in assets and liabilities:
Interest receivable	(1,547)	4,680
Other assets	(10,064)	(2,402)
Accrued interest and other liabilities	57,874	(58,284)
Income taxes payable	(245)	6,786
Net cash provided by operating activities	177,857	176,310
INVESTING ACTIVITIES
Net change in loans	(835,002)	1,520,504
Proceeds from sale of loans	15,556	1,847
Net change in due from banks - time	347	244
Purchases of premises and equipment, net	(17,000)	(5,829)
Proceeds from sale of premises and equipment	0	5,156
Proceeds from sale of foreclosed assets and other real estate owned	2,819	10,988
Proceeds from sale of available-for-sale securities	0	249,454
Proceeds from maturities of available-for-sale securities	762,094	314,547
Purchases of available-for-sale securities	(259,586)	(3,672,029)
Proceeds from maturities of held-to-maturity securities	30,848	9,479
Purchases of held-to-maturity securities	(329,660)	(606,187)
Purchases of bank owned life insurance death benefits	0	(160,000)
Proceeds from bank owned life insurance death benefits	0	3,032
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	(353,188)	(2,462,960)
FINANCING ACTIVITIES
Net change in deposits	(49,701)	1,307,965
Dividends paid on preferred stock	0	(26)
Dividends paid on common stock	(45,844)	(39,010)
Net change in other borrowed funds	(315,778)	(2,874)
Net change in federal funds purchased and securities sold under agreements to repurchase	(30,302)	(111,896)
Net shares issued (cancelled) under stock compensation plans	(3,905)	1,373
Shares issued under employee stock purchase plan	1,151	1,170
Repurchases of common stock	(66,096)	(3,080)
Net cash (used in) provided by financing activities	(510,475)	1,153,622
DECREASE IN CASH AND CASH EQUIVALENTS	(685,806)	(1,133,028)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	1,650,653	3,472,152
CASH AND CASH EQUIVALENTS, END OF PERIOD	$ 964,847	$ 2,339,124