Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net income	$ 34,396	$ 137,392
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	31,471	24,981
Provision for credit losses	217,804	9,220
Deferred income taxes	(31,577)	1,457
Gains on sale of securities, net	(15)	(2,687)
Trading securities revenue	(189)
Purchases of trading securities	(108,537)
Proceeds from sale of trading securities	108,726
Share-based compensation expense	18,694	6,642
Accretion of discount related to acquired loans	(43,484)	(9,131)
(Gains) losses on disposal of premises and equipment	(514)	3,648
Gains on sale of bank premises and other repossessed real estate	(21)	(527)
Net amortization of premiums on investment securities	13,318	5,310
Bank premises and other repossessed real estate write downs	770	727
Fair value adjustment for loans held for sale	(5,125)	1,463
Originations and purchases of loans held for sale	(1,943,097)	(583,804)
Proceeds from sales of loans held for sale	2,079,830	525,659
Gains on sales of loans held for sale	(74,808)	(7,786)
Bank owned life insurance income	(6,830)	(4,206)
Net change in:
Accrued interest receivable	(21,717)	(134)
Prepaid assets	(8,939)	(846)
Operating Leases	6,037	1,134
Bank owned life insurance	(1,231)	(218)
Derivative assets	(40,330)	(19,225)
Miscellaneous other assets	42,018	(27,477)
Accrued interest payable	678	317
Accrued income taxes	(30,106)	2,625
Derivative liabilities	60,536	38,866
Miscellaneous other liabilities	58,345	24,307
Net cash provided by operating activities	356,103	127,707
Cash flows from investing activities:
Proceeds from sales of investment securities available for sale	23,540	231,990
Proceeds from maturities and calls of investment securities available for sale	705,381	208,640
Proceeds from sales of other investment securities	42,034	45
Purchases of investment securities available for sale	(1,201,855)	(692,114)
Purchases of other investment securities	(80,513)	(23,566)
Net increase in loans	(737,130)	(280,684)
Net cash received from acquisitions	2,566,376
Recoveries of loans previously charged off	8,287	2,833
Purchases of premises and equipment	(13,009)	(11,533)
Proceeds from redemption and payout of bank owned life insurance policies	19,207	1,323
Proceeds from sale of bank premises and other repossessed real estate	8,254	7,405
Proceeds from sale of premises and equipment	704	17
Net cash provided by (used in) investing activities	1,341,276	(555,644)
Cash flows from financing activities:
Net increase in deposits	2,174,838	376,854
Net increase (decrease) in federal funds purchased and securities sold under agreements to repurchase and other short-term borrowings	6,436	(1,577)
Proceeds from borrowings	500,000	700,001
Repayment of borrowings	(500,005)	(150,005)
Common stock issuance	807	717
Common stock repurchases	(32,353)	(146,897)
Dividends paid on common stock	(64,907)	(42,175)
Stock options exercised	740	1,230
Net cash provided by financing activities	2,085,556	738,148
Net increase in cash and cash equivalents	3,782,935	310,211
Cash and cash equivalents at beginning of period	688,704	408,983
Cash and cash equivalents at end of period	4,471,639	719,194
Cash paid for:
Interest	73,525	65,237
Income taxes	62,555	31,928
Initial measurement and recognition of operating lease assets in exchange for lease liabilities per ASU 2016-02		82,160
Recognition of operating lease assets in exchange for lease liabilities	7,054	10,239
Acquisitions:
Fair value of tangible assets acquired	18,937,418
Other intangible assets acquired	140,862
Liabilities assumed	17,380,016
Net identifiable assets acquired over liabilities assumed	563,625
Common stock issued in acquisition	2,246,327
Real estate acquired in full or in partial settlement of loans	$ 4,262	$ 9,610