Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash Flows From Operating Activities
Net income	$ 149,604	$ 74,345
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation	14,068	15,053
Amortization of other intangible assets	5,984	7,388
Amortization of tax credit investments	3,015	5,802
Net premium amortization on investment securities	7,526	10,145
Accretion income related to acquired loans	(9,781)	(12,406)
Share-based compensation expense	3,563	4,228
Provision for credit losses	(22,285)	39,495
Debt securities (gains) losses, net	(2,685)	(5,685)
Net (gains) losses on sales of loans and other assets	(18,202)	7,760
Increase in cash surrender value of company-owned life insurance	(5,497)	(6,048)
Residential real estate loans originated for sale	(645,624)	(672,393)
Proceeds from sales of residential real estate loans	677,888	602,671
(Increase) decrease in interest receivable	(288)	737
(Increase) decrease in other assets	40,951	(88,376)
Increase (decrease) in accrued expenses and other liabilities	(33,062)	(19,284)
Net cash flows provided by (used in) operating activities	165,175	(36,568)
Cash Flows From Investing Activities
Purchases of investment securities available-for-sale	(1,801,957)	(1,154,055)
Purchases of Federal Home Loan Bank/Federal Reserve Bank stock	0	(10,025)
Proceeds from maturities, prepayments, and calls of investment securities available-for-sale	820,305	948,093
Proceeds from sales of investment securities available-for-sale	67,715	256,438
Proceeds from sales of Federal Home Loan Bank/Federal Reserve Bank stock	44	21
Proceeds from sales of equity securities	325	956
Loan originations and payments, net	11,924	(1,488,360)
Proceeds from company-owned life insurance death benefits	2,042	1,899
Proceeds from sales of premises and equipment and other assets	7,632	6,363
Purchases of premises and equipment and other assets	(34,411)	(18,714)
Net cash flows provided by (used in) investing activities	(926,381)	(1,457,384)
Net increase (decrease) in:
Deposits	831,458	1,766,049
Federal funds purchased and interbank borrowings	357	(349,613)
Securities sold under agreements to repurchase	(35,037)	39,962
Other borrowings	12,428	(5,407)
Payments for maturities of Federal Home Loan Bank advances	(145,005)	(250,005)
Payments for modification of Federal Home Loan Bank advances	(2,156)	0
Proceeds from Federal Home Loan Bank advances	50,000	455,770
Cash dividends paid on common stock	(46,397)	(46,648)
Common stock repurchased	(3,305)	(82,295)
Common stock issued	282	296
Net cash flows provided by (used in) financing activities	662,625	1,528,109
Net increase (decrease) in cash and cash equivalents	(98,581)	34,157
Cash and cash equivalents at beginning of period	589,712	276,337
Cash and cash equivalents at end of period	491,131	310,494
Supplemental cash flow information:
Total interest paid	22,368	42,278
Total taxes paid (net of refunds)	3,526	1,999
Investment securities purchased but not settled	8,046	36,681
Operating lease right-of-use assets obtained in exchange for lease obligations	499	(992)
Finance lease right-of-use assets obtained in exchange for lease obligations	$ 4,994	$ 5,225