Consolidated Statement of Cash Flows - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES
Net income		$ 703,701	$ 505,624	$ 431,677
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization		139,499	149,822	137,578
Accretion of discount and amortization of premiums, net		(20,572)	(7,260)	(26,024)
Stock compensation costs		30,937	24,657	22,102
Deferred income tax (benefit) expense		(16,470)	33,856	26,966
Provision for credit losses		64,255	46,266	27,479
Net gains on sales of loans		(6,590)	(8,870)	(6,085)
Net gains on sales of available-for-sale investment securities		(2,535)
Net gains on sales of available-for-sale investment securities			(8,037)	(10,362)
Net gains on sales of fixed assets		(6,683)	(77,388)	(3,178)
Net gain on sale of business		(31,470)	(3,807)	0
Loans held-for-sale:
Originations and purchases		(20,176)	(20,521)	(18,804)
Proceeds from sales and paydowns/payoffs of loans originally classified as held-for-sale		20,068	21,363	23,749
Proceeds from distributions received from equity method investees		3,761	3,582	4,690
Net change in accrued interest receivable and other assets		(60,791)	45,354	23,205
Net change in other liabilities		88,070	(1,965)	15,354
Other net operating activities		(1,832)	599	1,836
Total adjustments		179,471	197,651	218,506
Net cash provided by operating activities		883,172	703,275	650,183
Net (increase) decrease in:
Investments in qualified affordable housing partnerships, tax credit and other investments		(132,605)	(173,630)	(100,514)
Interest-bearing deposits with banks		4,212	(63,096)	(38,249)
Resale agreements:
Proceeds from paydowns and maturities		175,000	1,250,000	1,500,000
Purchases		(160,000)	(600,000)	(1,550,000)
Available-for-sale investment securities:
Proceeds from sales		364,270
Proceeds from sales			832,844	1,275,645
Proceeds from repayments, maturities and redemptions		742,132
Proceeds from repayments, maturities and redemptions			413,593	1,503,127
Purchases		(888,673)
Purchases			(828,604)	(2,396,199)
Loans held-for-investment:
Proceeds from sales of loans originally classified as held-for-investment		483,948	566,688	661,025
Purchases		(597,112)	(534,816)	(1,142,054)
Other changes in loans held-for-investment, net		(3,313,382)	(3,514,786)	(1,549,736)
Premises and equipment:
Proceeds from sales		1,638	119,749	8,163
Purchases		(13,787)	(13,754)	(12,181)
Sales of businesses, net of cash transferred:
Proceeds		0	3,633	0
Payments		503,687	0	0
Proceeds from sales of other real estate owned (“OREO”)		4,484	6,999	7,408
Proceeds from distributions received from equity method investees		5,185	8,387	7,964
Other net investing activities		(4,035)	19,969	25,515
Net cash provided by (used in) investing activities		(3,832,412)	(2,506,824)	(1,800,086)
CASH FLOWS FROM FINANCING ACTIVITIES
Net increase in deposits		3,903,192	2,272,500	2,452,870
Net increase (decrease) in short-term borrowings		61,392	(61,560)	62,506
Repayment of FHLB advances		0	0	(700,000)
Repayment of long-term debt		(25,000)	(15,000)	(20,000)
Common stock:
Proceeds from issuance pursuant to various stock compensation plans and agreements		2,846	2,280	2,081
Stocks tendered for payment of withholding taxes		(15,634)	(12,940)	(3,225)
Cash dividends paid		(125,988)	(116,820)	(115,828)
Other net financing activities		0	0	1,055
Net cash provided by (used in) by financing activities		3,800,808	2,068,460	1,679,459
Effect of exchange rate changes on cash and cash equivalents		(24,783)	31,178	(11,940)
NET INCREASE IN CASH AND CASH EQUIVALENTS		826,785	296,089	517,616
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR		2,174,592	1,878,503	1,360,887
CASH AND CASH EQUIVALENTS, END OF YEAR		3,001,377	2,174,592	1,878,503
Cash paid during the year for:
Interest		253,026	138,766	104,251
Income taxes, net		85,872	98,126	39,478
Noncash investing and financing activities:
Loans transferred from held-for-investment to held-for-sale	[1]	481,593	613,088	819,100
Loans transferred from held-for-sale to held-for-investment		2,306	0	4,943
Deposits transferred to branch liability held-for-sale		0	605,111	0
Investment security transferred from held-to-maturity to available-for-sale		0	115,615	0
Held-to-maturity investment security retained from securitization of loans		0	0	160,135
Premises and equipment transferred to branch assets held-for-sale		0	8,043	0
Loans transferred to OREO		$ 1,206	$ 777	$ 8,083

[1] December 31, 2017 amount includes loans transferred from held-for-investment to branch assets held-for-sale.