CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income	$ 309,793	$ 261,428	$ 161,907
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	53,317	27,554	24,845
Stock-based compensation	14,726	19,472	12,204
Provision for credit losses	24,218	32,501	9,942
Net amortization of premiums and accretion of discounts on securities and borrowings	29,512	38,454	46,346
Amortization of other intangible assets	18,080	18,416	10,016
Losses on securities transactions, net	150	2,342	20
Proceeds from sales of loans held for sale	1,743,470	687,983	813,855
Gains on sales of loans, net	(18,914)	(20,515)	(20,814)
Net impairment losses on securities recognized in earnings	2,928	0	0
Originations of loans held for sale	(537,985)	(406,087)	(444,290)
(Gains) losses on sales of assets, net	(78,333)	2,402	95
Net deferred income tax (benefit) expense	15,228	(11,780)	76,848
Net change in:
Cash surrender value of bank owned life insurance	(8,232)	(8,691)	(7,338)
Accrued interest receivable	1,440	(9,183)	(7,174)
Other assets	(163,330)	(33,145)	(57,353)
Accrued expenses and other liabilities	57,882	(7,562)	121
Net cash provided by operating activities	1,463,950	593,589	619,230
Cash flows from investing activities:
Net loan originations and purchases	(2,538,909)	(3,257,939)	(1,418,073)
Equity securities:
Purchases	(14,776)	0	0
Sales	24,748	0	0
Held to maturity debt securities:
Purchases	(701,879)	(264,721)	(220,356)
Maturities, calls and principal repayments	424,475	241,077	290,929
Available for sale debt securities:
Purchases	(30,392)	(289,554)	(411,788)
Sales	271,901	44,377	2,727
Maturities, calls and principal repayments	316,024	255,031	204,684
Death benefit proceeds from bank owned life insurance	9,560	4,220	13,089
Proceeds from sales of real estate property and equipment	109,043	7,786	9,357
Purchases of real estate property and equipment	(23,375)	(26,440)	(18,117)
Cash and cash equivalents acquired in acquisitions	22,239	156,612	0
Net cash used in investing activities	(2,131,341)	(3,129,551)	(1,547,548)
Cash flows from financing activities:
Net change in deposits	1,808,148	2,734,669	422,754
Net change in short-term borrowings	(1,036,134)	720,307	(332,332)
Proceeds from issuance of long-term borrowings, net	950,000	0	1,065,000
Repayments of long-term borrowings	(890,000)	(750,682)	(185,000)
Proceeds from issuance of preferred stock, net	0	0	98,101
Cash dividends paid to preferred shareholders	(12,688)	(15,859)	(6,277)
Cash dividends paid to common shareholders	(146,537)	(138,857)	(115,881)
Purchase of common shares to treasury	(1,805)	(3,801)	(2,645)
Common stock issued, net	2,957	2,704	8,207
Other, net	(492)	0	0
Net cash provided by financing activities	673,449	2,548,481	951,927
Net change in cash and cash equivalents	6,058	12,519	23,609
Cash and cash equivalents at beginning of year	428,629	416,110	392,501
Cash and cash equivalents at end of year	434,687	428,629	416,110
Supplemental disclosures of cash flow information:
Interest on deposits and borrowings	415,649	290,444	170,614
Federal and state income taxes	106,336	53,587	29,013
Supplemental schedule of non-cash investing activities:
Transfer of loans to other real estate owned	5,100	743	7,301
Loans transferred to loans held for sale	1,234,022	289,633	313,201
Lease right of use assets obtained in exchange for operating lease liabilities	312,143
Non-cash assets acquired:
Equity securities	51,382	0	0
Loans	3,380,841	3,736,984	0
Premises and equipment	23,585	62,066	0
Bank owned life insurance	101,896	49,052	0
Accrued interest receivable	11,781	12,123	0
Goodwill	288,960	394,028	0
Other intangible assets	20,690	45,906	0
Other assets	50,174	100,059	0
Total non-cash assets acquired	4,270,080	4,922,820	0
Liabilities assumed:
Deposits	2,924,716	3,564,843	0
Short-term borrowings	10,500	649,979	0
Long-term borrowings	430,130	87,283	0
Junior subordinated debentures issued to capital trusts	0	13,249	0
Accrued expenses and other liabilities	91,718	26,848	0
Total liabilities assumed	3,457,064	4,342,202	0
Net non-cash assets acquired	813,016	580,618	0
Net cash and cash equivalents acquired in acquisition	22,239	156,612	0
Common stock issued in acquisition	835,255	737,230	0
Available-for-sale securities
Non-cash assets acquired:
Investment securities	335,894	308,385	0
Held-to-maturity securities
Non-cash assets acquired:
Investment securities	$ 4,877	$ 214,217	$ 0