Condensed 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	$ 270,345	$ 235,952
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of investment premiums, net	19,592	15,485
Loss (gain) on sale of investment securities, net	7,186	(14)
Loss (gain) on sale of other real estate owned, net	802	(324)
Valuation adjustment on other real estate owned	3,013	66
Provision for loan and lease losses	56,263	38,686
Change in cash surrender value of bank owned life insurance	(6,365)	(6,281)
Depreciation, amortization and accretion	33,126	40,015
Gain on sale of premises and equipment	(1,568)	(2,365)
Gain on store divestiture	(1,225)	(1,157)
Additions to residential mortgage servicing rights carried at fair value	16,772	22,012
Change in fair value of residential mortgage servicing rights carried at fair value	34,414	125
Gain on redemption of junior subordinated debentures at amortized cost	0	(1,043)
Stock-based compensation	5,826	5,519
Net increase in equity and other investments	(1,217)	(123)
(Gain) loss on equity securities, net	(83,559)	1,894
Gain on sale of loans and leases, net	(65,707)	(59,485)
Change in fair value of loans held for sale	(5,758)	1,103
Origination of loans held for sale	(2,029,682)	(2,283,639)
Proceeds from sales of loans held for sale	1,906,722	2,306,652
Change in other assets and liabilities:
Net (increase) decrease in other assets	(183,131)	6,167
Net (decrease) increase in other liabilities	(20,180)	43,380
Net cash (used in) provided by operating activities	(77,875)	318,601
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of investment securities available for sale	(563,606)	(283,948)
Proceeds from investment securities available for sale	778,259	341,680
Proceeds from investment securities held to maturity	432	385
Proceeds from sale of equity securities	81,853	0
Purchases of restricted equity securities	(220,200)	(45,601)
Redemption of restricted equity securities	206,005	48,840
Net change in loans and leases	(1,235,214)	(991,726)
Proceeds from sales of loans and leases	88,776	119,783
Change in premises and equipment	(8,230)	(5,686)
Proceeds from bank owned life insurance death benefits	1,869	1,481
Proceeds from sales of other real estate owned	5,835	2,805
Net cash paid in store divestiture	(44,646)	(35,219)
Net cash used in investing activities	(908,867)	(847,206)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase in deposit liabilities	1,347,046	981,648
Net decrease in securities sold under agreements to repurchase	(434)	(7,324)
Proceeds from borrowings	810,670	50,000
Repayment of borrowings	(455,670)	(100,652)
Repayment of junior subordinated debentures at amortized cost	0	(10,598)
Dividends paid on common stock	(138,856)	(127,662)
Proceeds from stock options exercised	21	1,065
Repurchase and retirement of common stock	(7,228)	(12,893)
Net cash provided by financing activities	1,555,549	773,584
Net increase in cash and cash equivalents	568,807	244,979
Cash and cash equivalents, beginning of period	622,637	634,280
Cash and cash equivalents, end of period	1,191,444	879,259
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Interest	155,232	83,255
Income taxes	107,933	49,475
SUPPLEMENTAL DISCLOSURE OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Changes in unrealized gains and losses on investment securities available for sale, net of taxes	79,900	(56,219)
Changes in unrealized gains and losses on junior subordinated debentures carried at fair value, net of taxes	23,978	(4,174)
Junior subordinated debentures, at fair value, cumulative effect adjustment	0	9,710
Cash dividend declared on common stock and payable after period-end	46,245	46,253
Change in GNMA mortgage loans recognized due to repurchase option	(3,690)	(4,407)
Transfer of loans to other real estate owned	$ 2,718	$ 2,587