Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019
Cash Flows From Operating Activities
Net income		$ 74,345	$ 119,240
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation		15,053	13,171
Amortization of other intangible assets		7,388	8,797
Amortization of tax credit investments		5,802	828
Net premium amortization on investment securities		10,145	6,852
Accretion income related to acquired loans		(12,406)	(20,257)
Share-based compensation expense		4,228	3,746
Excess tax (benefit) expense on share-based compensation		(734)	(1,053)
Provision for loan losses	[1]	39,495	2,046
Debt securities (gains) losses, net		(5,685)	(1,062)
Net (gains) losses on sales of loans and other assets		7,760	227
Increase in cash surrender value of company-owned life insurance		(6,048)	(5,899)
Residential real estate loans originated for sale		(672,393)	(282,134)
Proceeds from sales of residential real estate loans		602,671	263,028
(Increase) decrease in interest receivable		737	(1,079)
(Increase) decrease in other assets		(87,642)	12,344
Increase (decrease) in accrued expenses and other liabilities		(19,284)	(45,426)
Net cash flows provided by (used in) operating activities		(36,568)	73,369
Cash Flows From Investing Activities
Purchases of investment securities available-for-sale		(1,154,055)	(1,038,437)
Purchases of Federal Home Loan Bank/Federal Reserve Bank stock		(10,025)	(14,439)
Proceeds from maturities, prepayments, and calls of investment securities available-for-sale		948,093	335,035
Proceeds from sales of investment securities available-for-sale		256,438	267,632
Proceeds from maturities, prepayments, and calls of investment securities held-to-maturity		0	35,958
Proceeds from sales of Federal Home Loan Bank/Federal Reserve Bank stock		21	19
Proceeds from sales of equity securities		956	130
Loan originations and payments, net		(1,488,360)	216,356
Proceeds from company-owned life insurance death benefits		1,899	4,374
Proceeds from sales of premises and equipment and other assets		6,363	2,534
Purchases of premises and equipment and other assets		(18,714)	(24,002)
Net cash flows provided by (used in) investing activities		(1,457,384)	(214,840)
Net increase (decrease) in:
Deposits		1,766,049	13,152
Federal funds purchased and interbank borrowings		(349,613)	139,901
Securities sold under agreements to repurchase		39,962	(27,754)
Other borrowings		(5,407)	3,864
Payments for maturities of Federal Home Loan Bank advances		(250,005)	(325,999)
Proceeds from Federal Home Loan Bank advances		455,770	425,000
Cash dividends paid on common stock		(46,648)	(45,288)
Common stock repurchased		(82,295)	(58,142)
Proceeds from exercise of stock options		0	280
Common stock issued		296	278
Net cash flows provided by (used in) financing activities		1,528,109	125,292
Net increase (decrease) in cash and cash equivalents		34,157	(16,179)
Cash and cash equivalents at beginning of period		276,337	317,165
Cash and cash equivalents at end of period		310,494	300,986
Supplemental cash flow information:
Total interest paid		42,278	66,419
Total taxes paid (net of refunds)		1,999	1,204
Investment securities purchased but not settled		36,681	1,424
Operating lease right-of-use assets obtained in exchange for lease obligations		(992)
Operating lease right-of-use assets obtained in exchange for lease obligations			117,751
Finance lease right-of-use assets obtained in exchange for lease obligations		$ 5,225	$ 7,871

[1] Beginning January 1, 2020, calculation is based on current expected loss methodology. Prior to January 1, 2020, calculation was based on incurred loss methodology.