Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
OPERATING ACTIVITIES
Net income	$ 271,156	$ 254,904	$ 238,167
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	47,220	49,038	36,257
Provision for credit losses	(32,704)	74,973	43,240
Gain on sale of investments	(15,498)	(54,806)	(13,314)
Net accretion of investment securities and assets	(52,781)	(56,771)	(53,619)
Net amortization on borrowings	1,257	541	394
Stock-based compensation expense	15,868	13,197	12,921
Gain on sale of premises and equipment, net of impairment	(591)	(14)	0
Gain on sale of foreclosed assets and other real estate owned	(932)	(391)	(33)
Gain on sale of mortgage loans held for sale	(36,434)	(44,864)	(20,064)
Gain on sale of other intangibles	0	(301)	0
Gain on sale of branches	(5,316)	(8,094)	0
Loss on sale of loans	0	0	4,451
Gain on sale of Visa, Inc. class B common stock	0	0	(42,860)
Fair value write-down of closed branches	0	434	0
Deferred income taxes	10,937	(122)	34,911
Income from bank owned life insurance	(9,477)	(7,206)	(4,854)
Originations of mortgage loans held for sale	(1,034,716)	(1,206,818)	(755,500)
Proceeds from sale of mortgage loans held for sale	1,190,891	1,172,406	756,642
Changes in assets and liabilities:
Interest receivable	4,423	(10,846)	3,231
Other assets	(33,495)	(7,480)	31,920
Accrued interest and other liabilities	(50,620)	50,508	(35,886)
Income taxes payable	8,592	(15,745)	20,074
Net cash provided by operating activities	277,780	202,543	256,078
INVESTING ACTIVITIES
Net collections (originations) of loans	2,333,893	1,327,248	23,806
Proceeds from sale of loans	28,033	49,736	104,587
Decrease in due from banks - time	292	2,975	1,130
Purchases of premises and equipment, net	(47,861)	(13,272)	(67,831)
Proceeds from sale of premises and equipment	5,621	369	0
Proceeds from sale of foreclosed assets and other real estate owned	21,983	10,788	17,986
Proceeds from sale of available-for-sale securities	342,577	1,717,364	1,226,578
Proceeds from maturities of available-for-sale securities	1,001,669	2,346,930	793,270
Purchases of available-for-sale securities	(5,266,148)	(4,140,963)	(1,708,948)
Proceeds from maturities of held-to-maturity securities	15,712	13,970	31,969
Purchases of held-to-maturity securities	(708,580)	(308,854)	0
Proceeds from bank owned life insurance death benefits	3,814	2,018	2,435
Purchases of bank owned life insurance	(160,000)	0	0
Cash received in business combinations, net	25,425	0	178,260
Disposition of assets and liabilities held for sale	(134,166)	181,560	1,235
Net cash provided by (used in) investing activities	(2,537,736)	1,189,869	604,477
FINANCING ACTIVITIES
Net change in deposits	847,494	1,086,713	(404,826)
Proceeds from issuance of other borrowings	0	0	25,500
Repayments of subordinated debentures	(1,563)	(7,442)	0
Dividends paid on preferred stock	(47)	(52)	(339)
Dividends paid on common stock	(78,845)	(74,593)	(63,921)
Net change in other borrowed funds	(80,254)	45,983	(240,806)
Net change in federal funds purchased and securities sold under agreements to repurchase	(116,562)	148,966	40,207
Net shares (cancelled) issued under stock compensation plans	290	(4,087)	(2,389)
Shares issued under employee stock purchase plan	1,170	956	1,312
Repurchase of common stock	(132,459)	(113,327)	(10,128)
Retirement of preferred stock	(767)	0	(42,000)
Net cash provided by (used in) financing activities	438,457	1,083,117	(697,390)
INCREASE (DECREASE) IN CASH EQUIVALENTS	(1,821,499)	2,475,529	163,165
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR	3,472,152	996,623	833,458
CASH AND CASH EQUIVALENTS, END OF YEAR	$ 1,650,653	$ 3,472,152	$ 996,623