Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net income	$ 216,556	$ 204,399
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan and lease losses	9,550	16,430
Depreciation, amortization and accretion, net	49,976	41,893
Deferred income taxes	19,124	2,208
Stock-based compensation	4,707	4,884
Other losses (gains)	18	(897)
Originations of loans held for sale	(12,960)	(28,472)
Proceeds from sales of loans held for sale	11,856	28,614
Net losses (gains) on sales of loans originated for investment and held for sale	1,156	(148)
Net losses on investment securities	2,592
Change in assets and liabilities:
Net (increase) decrease in other assets	(46,083)	5,573
Net decrease in other liabilities	(85,425)	(8,973)
Net cash provided by operating activities	171,067	265,511
Available-for-sale securities:
Proceeds from maturities and principal repayments	536,058	637,538
Proceeds from calls and sales	943,630
Purchases	(999,490)	(130,251)
Other investments:
Proceeds from sales	9,238	10,333
Purchases	(19,429)	(45,432)
Loans:
Net decrease (increase) in loans and leases resulting from originations and principal repayments	55,138	(171,306)
Proceeds from sales of loans originated for investment	407,698	562
Purchases of loans	(247,711)	(158,616)
Proceeds from bank-owned life insurance	5,612	1,154
Purchases of premises, equipment and software	(22,370)	(13,495)
Purchases of mortgage servicing rights		(6,444)
Proceeds from sales of other real estate owned	759	332
Other	(2,023)	(2,054)
Net cash provided by investing activities	667,110	122,321
Cash flows from financing activities
Net decrease in deposits	(292,822)	(922,849)
Net increase in short-term borrowings		30,000
Proceeds from long-term borrowings		400,000
Repayment of long-term borrowings	(10)	(10)
Dividends paid	(104,392)	(98,666)
Stock tendered for payment of withholding taxes	(1,764)
Proceeds from employee stock purchase plan		342
Common stock repurchased	(98,809)	(131,800)
Net cash used in financing activities	(497,797)	(722,983)
Net increase (decrease) in cash and cash equivalents	340,380	(335,151)
Cash and cash equivalents at beginning of period	1,003,637	1,034,644
Cash and cash equivalents at end of period	1,344,017	699,493
Supplemental disclosures
Interest paid	80,886	56,430
Income taxes paid, net of income tax refunds	69,173	29,204
Noncash investing and financing activities:
Transfers from loans and leases to other real estate owned	75	$ 143
Operating lease right-of-use assets obtained in exchange for new lease obligations	1,401
Transfers from loans and leases to loans held for sale	$ 408,912