Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
OPERATING ACTIVITIES
Net income	$ 142,344	$ 136,038
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Depreciation and amortization	23,837	24,148
Provision for credit losses	(11,506)	45,049
Gain on sale of investments	(10,598)	(32,485)
Net accretion of investment securities and assets	(24,377)	(30,078)
Net amortization on borrowings	269	271
Stock-based compensation expense	7,592	7,577
Gain on sale of premises held for sale	(606)	0
Gain on sale of foreclosed assets held for sale	(177)	(400)
Gain on sale of mortgage loans held for sale	(20,006)	(14,993)
Gain on sale of other intangibles	0	(301)
Gain on sale of banking operations	(5,300)	(8,094)
Fair value write-down of closed branches	0	1,465
Deferred income taxes	6,315	4,616
Income from bank owned life insurance	(3,630)	(3,245)
Originations of mortgage loans held for sale	(534,124)	(470,797)
Proceeds from sale of mortgage loans held for sale	655,497	423,858
Changes in assets and liabilities:
Interest receivable	4,680	(18,021)
Other assets	(2,402)	(19,676)
Accrued interest and other liabilities	(58,284)	76,265
Income taxes payable	6,786	(34,233)
Net cash provided by operating activities	176,310	86,964
INVESTING ACTIVITIES
Net change in loans	1,520,504	(318,795)
Proceeds from sale of loans	1,847	4,600
Net change in due from banks - time	244	(7)
Purchases of premises and equipment, net	(5,829)	(19,784)
Proceeds from sale of premises held for sale	5,156	0
Proceeds from sale of foreclosed assets held for sale	10,988	6,173
Proceeds from sale of available-for-sale securities	249,454	1,201,778
Proceeds from maturities of available-for-sale securities	314,547	2,048,453
Purchases of available-for-sale securities	(3,672,029)	(2,386,878)
Proceeds from maturities of held-to-maturity securities	9,479	5,932
Purchases of held-to-maturity securities	(606,187)	(16,997)
Purchase of bank owned life insurance	(160,000)	0
Proceeds from bank owned life insurance death benefits	3,032	763
Disposition of assets and liabilities held for sale	(134,166)	181,261
Net cash (used in) provided by investing activities	(2,462,960)	706,499
FINANCING ACTIVITIES
Net change in deposits	1,307,965	561,185
Repayments of subordinated debentures	0	(5,927)
Dividends paid on preferred stock	(26)	(26)
Dividends paid on common stock	(39,010)	(37,606)
Net change in other borrowed funds	(2,874)	96,090
Net change in federal funds purchased and securities sold under agreements to repurchase	(111,896)	236,880
Net shares issued (cancelled) under stock compensation plans	1,373	(3,171)
Shares issued under employee stock purchase plan	1,170	956
Repurchases of common stock	(3,080)	(93,307)
Net cash provided by financing activities	1,153,622	755,074
(DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(1,133,028)	1,548,537
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	3,472,152	996,623
CASH AND CASH EQUIVALENTS, END OF PERIOD	$ 2,339,124	$ 2,545,160