CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Operating activities:
Net income	$ 118,191	$ 126,179
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	11,946	11,781
Amortization of intangible assets	10,772	11,994
Net accretion on securities, loans and borrowings	(7,954)	(4,545)
Stock-based compensation	4,648	3,998
Provision for credit losses	17,313	5,573
Amortization of mortgage servicing rights	266	285
Gain on sale of investment securities, net	0	(4,882)
Unrealized loss (gain) on equity securities	30	(28)
Income from bank-owned life insurance policies	(1,398)	(1,215)
Net gain on sale of loans and other assets	(1,633)	(2)
Change in other assets and other liabilities	(26,944)	(20,152)
Net cash provided by operating activities	125,237	128,986
Investing activities:
Proceeds from sales of available-for-sale investment securities	0	590,179
Proceeds from maturities, calls, and paydowns of available-for-sale investment securities	219,503	153,785
Proceeds from maturities and redemptions of equity and other investment securities	436	3,258
Purchases of available-for-sale investment securities	(91,381)	(86,073)
Purchases of equity and other securities	(3,064)	(144)
Net increase in loans	(228,235)	(100,020)
Cash received (paid) for acquisitions, net of cash acquired of $55,973 and $90,381, respectively	34,360	(4,653)
Settlement of bank-owned life insurance policies	0	1,597
Purchases of premises and equipment, net	(8,727)	(5,025)
Real estate tax credit investments	(1,071)	(1,342)
Net cash (used in) provided by investing activities	(78,179)	551,562
Financing activities:
Net increase in deposits	1,609,349	277,833
Net increase (decrease) in borrowings	28,690	(80,502)
Payments on subordinated debt held by unconsolidated subsidiary trusts	(2,062)	(22,681)
Issuance of common stock	14,141	2,512
Purchases of treasury stock	(204)	(213)
Sales of treasury stock	85	6,662
Increase in deferred compensation arrangements	204	213
Cash dividends paid	(64,593)	(59,014)
Withholding taxes paid on share-based compensation	(1,177)	(3,150)
Net cash provided by financing activities	1,584,433	121,660
Change in cash and cash equivalents	1,631,491	802,208
Cash and cash equivalents at beginning of period	205,030	211,834
Cash and cash equivalents at end of period	1,836,521	1,014,042
Supplemental disclosures of cash flow information:
Cash paid for interest	16,927	18,455
Cash paid for income taxes	28,705	34,150
Supplemental disclosures of noncash financing and investing activities:
Dividends declared and unpaid	22,658	21,282
Transfers from loans to other real estate	1,192	1,833
Acquisitions:
Common stock issued	76,942	0
Fair value of assets acquired, excluding acquired cash and intangibles	547,623	548,856
Fair value of liabilities assumed	$ 529,441	$ 589,396