Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash Flows From Operating Activities
Net income	$ 56,276	$ 47,983
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation	6,443	5,833
Amortization of other intangible assets	4,472	3,609
Amortization of tax credit investments	260	716
Net premium amortization on investment securities	3,154	3,845
Accretion income related to acquired loans	(8,668)	(10,914)
Share-based compensation expense	1,800	1,931
Excess tax (benefit) expense on share-based compensation	(1,013)	536
Provision for loan losses	1,043	380
Net debt securities (gains) losses	103	(788)
Net (gains) losses on sales of loans and other assets	(1,564)	5,365
Increase in cash surrender value of company-owned life insurance	(3,188)	(2,605)
Residential real estate loans originated for sale	(94,632)	(92,377)
Proceeds from sales of residential real estate loans	97,010	93,686
(Increase) decrease in interest receivable	3,184	5,481
(Increase) decrease in other real estate owned	(47)	2,075
(Increase) decrease in other assets	13,665	9,211
Increase (decrease) in accrued expenses and other liabilities	(34,376)	(22,567)
Total adjustments	(12,354)	3,417
Net cash flows provided by (used in) operating activities	43,922	51,400
Cash Flows From Investing Activities
Purchases of investment securities available-for-sale	(541,589)	(113,525)
Purchases of Federal Home Loan Bank/Federal Reserve Bank stock	(14,439)	(16,520)
Proceeds from maturities, prepayments, and calls of investment securities available-for-sale	145,356	118,694
Proceeds from sales of investment securities available-for-sale	8,681	84,257
Proceeds from maturities, prepayments, and calls of investment securities held-to-maturity	21,689	26,117
Proceeds from sales of Federal Home Loan Bank/Federal Reserve Bank stock	19
Proceeds from sales of equity securities	130	128
Net principal collected from (loans made to) loan customers	182,638	(110,027)
Proceeds from settlements on company-owned life insurance	2,861	1,797
Proceeds from sales of premises and equipment and other assets	84	2,578
Purchases of premises and equipment and other assets	(11,684)	(9,593)
Net cash flows provided by (used in) investing activities	(206,254)	(16,094)
Cash Flows From Financing Activities
Deposits	79,321	182,697
Federal funds purchased and interbank borrowings	54,895	(185,007)
Securities sold under agreements to repurchase	(19,814)	(76,621)
Other borrowings	3,650	(32)
Payments for maturities of Federal Home Loan Bank advances	(325,070)	(772,928)
Proceeds from Federal Home Loan Bank advances	425,000	825,000
Cash dividends paid on common stock	(22,812)	(19,782)
Common stock repurchased	(27,297)	(1,115)
Proceeds from exercise of stock options	280	186
Common stock issued	130	105
Net cash flows provided by (used in) financing activities	168,283	(47,497)
Net increase (decrease) in cash and cash equivalents	5,951	(12,191)
Cash and cash equivalents at beginning of period	317,165	290,432
Cash and cash equivalents at end of period	323,116	278,241
Supplemental cash flow information:
Total interest paid	33,779	20,775
Total taxes paid (net of refunds)	150	(183)
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