Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating activities:
Net income	$ 269,801	$ 164,089	$ 185,721
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion, net	(2,063)	(8,586)	23,952
(Release of) provision for credit losses	(37,550)	80,434	13,150
Stock-based compensation	6,554	7,887	9,360
Deferred income tax expense	20,787	2,668	14,909
Securities (gains) losses, net	(83)	(748)	1,021
Gains from other loan sales, net	(11,267)	(5,420)	(6,867)
Changes in assets and liabilities:
Decrease (increase) in other assets and accrued interest receivable	53,416	(20,139)	(45,789)
Decrease in accrued expenses and other liabilities	(1,599)	(14,783)	(1,975)
Decrease (increase) in loans held for sale	61,324	(46,721)	(39,549)
Net cash provided by operating activities	359,320	158,681	153,933
Debt securities held-to-maturity:
Proceeds from maturities and calls	68,319	57,981	50,379
Purchases	(806,405)	(157,465)	(59,629)
Debt securities available-for-sale and equity securities with readily determinable fair values:
Proceeds from sales	288,986	40,625	352,106
Proceeds from maturities and calls	974,721	834,725	349,758
Purchases	(2,587,420)	(1,456,311)	(294,245)
Payments for (Proceeds from) Loans and Leases	178,234	(1,069,089)	(205,612)
Equity investments, outflows	(15,595)	(15,885)	0
Equity investments, inflows	8,481	401	0
Net cash received in (paid for) acquisitions	103,065	195,699	(19,545)
Purchases of premises and equipment	(26,483)	(18,462)	(20,944)
Proceeds from sales of premises and equipment	4,247	903	6,595
Proceeds from sale of other real estate owned	3,290	1,074	2,439
Other investing outflows	(610)	0	0
Other investing inflows	767	5,241	1,916
Net cash (used in) provided by investing activities	(1,806,403)	(1,580,563)	163,218
Financing activities:
Net increase in deposits	2,353,451	2,534,471	151,401
Proceeds from Federal Home Loan Bank advances	10,000	5,000	1,625,000
Repayment of Federal Home Loan Bank advances	(34,509)	(134,121)	(1,785,000)
Repayment of long-term debt	(80,632)	0	(55,266)
Proceeds from issuance of long-term debt, net of issuance costs	0	98,552	0
Proceeds from issuance of common stock for dividend reinvestment and employee benefit plans	506	1,317	2,193
Proceeds from exercise of options and warrants	231	0	212
Cash paid for shares withheld to cover payroll taxes related to equity instruments	(3,182)	(3,119)	(1,686)
Repurchase of common stock	(15,101)	(20,782)	(13,020)
Proceeds from issuance of Series I preferred stock, net of issuance costs	0	96,422	0
Cash dividends on common stock	(66,914)	(58,912)	(53,044)
Cash dividends on preferred stock	(6,876)	(3,533)	0
Net cash provided by (used in) financing activities	2,156,974	2,515,295	(129,210)
Net change in cash and cash equivalents	709,891	1,093,413	187,941
Cash and cash equivalents at beginning of year	1,608,619	515,206	327,265
Cash and cash equivalents at end of year	$ 2,318,510	$ 1,608,619	$ 515,206