Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash Flows From Operating Activities
Net income	$ 189,021	$ 143,332
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation	19,980	17,666
Amortization of other intangible assets	12,965	10,308
Amortization of tax credit investments	2,039	21,807
Net premium amortization on investment securities	13,199	11,290
Accretion income related to acquired loans	(33,465)	(29,525)
Share-based compensation expense	5,946	5,629
Excess tax (benefit) expense on share-based compensation	(1,057)	416
Provision for loan losses	3,483	3,576
Net debt securities (gains) losses	(1,486)	(2,417)
Net (gains) losses on sales of loans and other assets	(3,815)	(215)
Increase in cash surrender value of company-owned life insurance	(8,602)	(7,993)
Residential real estate loans originated for sale	(564,457)	(377,702)
Proceeds from sales of residential real estate loans	528,739	378,849
(Increase) decrease in interest receivable	8,717	5,112
(Increase) decrease in other assets	(1,695)	5,947
Increase (decrease) in accrued expenses and other liabilities	(32,816)	(7,866)
Net cash flows provided by (used in) operating activities	136,696	178,214
Cash Flows From Investing Activities
Purchases of investment securities available-for-sale	(1,713,799)	(446,276)
Purchases of Federal Home Loan Bank/Federal Reserve Bank stock	(21,142)	(16,520)
Proceeds from maturities, prepayments, and calls of investment securities available-for-sale	810,397	316,239
Proceeds from sales of investment securities available-for-sale	295,615	136,648
Proceeds from maturities, prepayments, and calls of investment securities held-to-maturity	99,913	49,520
Proceeds from sales of Federal Home Loan Bank/Federal Reserve Bank stock	21	0
Proceeds from sales of equity securities	130	128
Proceeds from sale of student loan portfolio		70,674
Loan originations and payments, net	257,675	(211,199)
Proceeds from company-owned life insurance death benefits	5,716	6,501
Proceeds from sales of premises and equipment and other assets	3,038	6,013
Purchases of premises and equipment and other assets	(31,095)	(24,704)
Net cash flows provided by (used in) investing activities	(293,531)	(112,976)
Cash Flows From Financing Activities
Deposits	98,403	(7,703)
Federal funds purchased and interbank borrowings	(29,546)	114,998
Securities sold under agreements to repurchase	(24,743)	(64,979)
Other borrowings	3,744	2,427
Payments for maturities of Federal Home Loan Bank advances	(375,999)	(998,801)
Proceeds from Federal Home Loan Bank advances	750,000	945,000
Cash dividends paid on common stock	(67,424)	(59,394)
Common stock repurchased	(95,214)	(1,776)
Proceeds from exercise of stock options	280	948
Common stock issued	419	371
Net cash flows provided by (used in) financing activities	259,920	(68,909)
Net increase (decrease) in cash and cash equivalents	103,085	(3,671)
Cash and cash equivalents at beginning of period	317,165	290,432
Cash and cash equivalents at end of period	420,250	286,761
Supplemental cash flow information:
Total interest paid	101,224	65,880
Total taxes paid (net of refunds)	2,954	1,681
Investment securities purchased but not settled	64,924	2,291
Securities transferred from held-to-maturity to available-for-sale	0	447,026
Securities transferred from available-for-sale to held-to-maturity	0	323,990
Operating lease right-of-use assets obtained in exchange for lease obligations	117,853	0
Finance lease right-of-use assets obtained in exchange for lease obligations	$ 7,871	$ 0