Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Operating activities:
Net income	$ 104,587	$ 136,709
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion	5,332	18,009
Provision for credit losses	77,527	9,650
Stock based compensation	5,939	7,680
Deferred income tax expense	189	12,149
Securities (gains) losses, net	(746)	118
Gains from sales of other loans	(3,889)	(4,783)
Changes in assets and liabilities:
Other assets and accrued interest receivable	(44,570)	(47,543)
Accrued expenses and other liabilities	(20,869)	(188)
Loans held for sale	(69,875)	(35,690)
Net cash provided by operating activities	53,625	96,111
Debt securities held-to-maturity:
Proceeds from maturities and calls	45,171	39,787
Purchases	(105,622)	(8,499)
Debt securities available-for-sale and equity securities:
Proceeds from sales	40,365	225,883
Proceeds from maturities and calls	604,180	238,514
Purchases	(668,484)	(45,629)
Net increase in loans	(1,523,516)	(296,076)
Proceeds from sales of premises and equipment	641	5,870
Purchases of premises and equipment	(5,991)	(16,532)
Net cash received in (paid for) acquisition	194,606	(19,545)
Proceeds from sale of other real estate	466	2,344
Other investing activities, net	(8,185)	0
Net cash (used in) provided by investing activities	(1,426,369)	126,117
Financing activities:
Net increase in deposits	1,904,549	10,538
Repayment of long-term debt	0	(27,500)
Proceeds from FHLB advances	5,000	1,625,000
Repayment of FHLB advances	(134,121)	(1,745,000)
Proceeds from issuance of senior debentures, net of issuance costs	98,552	0
Proceeds from issuance of common stock for dividend reinvestment and employee benefit plans	1,078	2,004
Proceeds from exercise of stock options	0	197
Cash paid for shares withheld to cover payroll taxes upon vesting of restricted stock units	(2,640)	(1,261)
Proceeds from issuance of Series I preferred stock, net of issuance costs	96,422	0
Repurchase of common stock	(20,782)	(13,020)
Cash dividends on common stock	(43,067)	(39,392)
Cash dividends on preferred stock	(1,814)	0
Net cash provided by (used in) financing activities	1,903,177	(188,434)
Net change in cash and cash equivalents, including restricted cash	530,433	33,794
Cash and cash equivalents, including restricted cash, at beginning of period	515,206	327,265
Cash and cash equivalents, including restricted cash, at end of period	1,045,639	361,059
Significant non-cash investing and financing transactions:
Unsettled government guaranteed loan sales	328	6,850
Transfers of loans to foreclosed properties	586	853
Unsettled securities purchases	30,045	0
Acquisitions:
Assets acquired	2,174,723	264,937
Liabilities assumed	1,987,026	212,844
Net assets acquired	187,697	52,093
Common stock issued for acquisition	$ 163,589	$ 0