Consolidated Statement of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 567,797	$ 674,035	$ 703,701
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	210,653	98,685	64,255
Depreciation and amortization	119,908	144,178	139,499
Accretion of discount and amortization of premiums, net	(16,456)	(22,379)	(20,572)
Stock compensation costs	29,237	30,761	30,937
Deferred income tax benefit	(41,515)	(21,604)	(16,470)
Net gains on sales of loans	(4,501)	(4,035)	(6,590)
Gains on sales of AFS debt securities	(12,299)	(3,930)	(2,535)
Net gain on sale of business	0	0	(31,470)
Loans held-for-sale:
Originations and purchases	(81,662)	(10,569)	(20,176)
Proceeds from sales and paydowns/payoffs of loans originally classified as held-for-sale	80,659	10,436	20,068
Proceeds from distributions received from equity method investees	8,786	3,470	3,761
Net change in accrued interest receivable and other assets	(339,868)	(170,819)	(60,791)
Net change in other liabilities	170,403	7,012	88,070
Other net operating activities	2,183	588	(8,515)
Total adjustments	125,528	61,794	179,471
Net cash provided by operating activities	693,325	735,829	883,172
Net Increase (Decrease) in Cash Flows from Investing Activities:
Investments in qualified affordable housing partnerships, tax credit and other investments	(154,887)	(146,902)	(132,605)
Interest-bearing deposits with banks	(577,607)	193,455	4,212
Resale agreements:
Proceeds from paydowns and maturities	450,000	650,000	175,000
Purchases	(800,000)	(325,000)	(160,000)
AFS debt securities:
Proceeds from sales	525,433	627,110	364,270
Proceeds from repayments, maturities and redemptions	2,070,131	1,155,002	742,132
Purchases	(4,758,254)	(2,303,317)	(888,673)
Loans held-for-investment:
Proceeds from sales of loans originally classified as held-for-investment	331,864	288,823	483,948
Purchases	(389,863)	(524,142)	(597,112)
Other changes in loans held-for-investment, net	(3,557,369)	(2,184,915)	(3,313,382)
Premises and equipment:
Proceeds from sales	5,154	403	1,638
Purchases	(2,656)	(9,859)	(13,787)
Payment received from the sales of businesses, net of cash transferred	0	0	(503,687)
Distributions received from equity method investees	15,901	9,502	5,185
Other net investing activities	(6,563)	(1,336)	449
Net cash provided by (used in) investing activities	(6,848,716)	(2,571,176)	(3,832,412)
CASH FLOWS FROM FINANCING ACTIVITIES
Net increase in deposits	7,482,730	1,902,741	3,903,192
Net (decrease) increase in short-term borrowings	(9,016)	(28,535)	61,392
FHLB advances:
Proceeds	10,300	1,500,000	0
Repayments	(105,300)	(1,082,001)	0
Repurchase agreements:
Proceeds	48,063	0	0
Repayment	(198,063)	0	0
Extinguishment cost	(8,740)	0	0
Long-term debt and lease liabilities:
Proceeds from long-term debt	1,437,269	0	0
Repayments of long-term debt and lease liabilities	(1,438,335)	(884)	(25,000)
Common stock:
Proceeds from issuance pursuant to various stock compensation plans and agreements	2,326	3,383	2,846
Stocks tendered for payment of withholding taxes	(8,253)	(14,635)	(15,634)
Repurchase of common stocks pursuant to the Stock Repurchase Program	(145,966)	0	0
Cash dividends paid	(158,222)	(155,107)	(125,988)
Other net financing activities	0	0	0
Net cash provided by (used in) financing activities	6,908,793	2,124,962	3,800,808
Effect of exchange rate changes on cash and cash equivalents	3,420	(29,843)	(24,783)
NET INCREASE IN CASH AND CASH EQUIVALENTS	756,822	259,772	826,785
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR	3,261,149	3,001,377	2,174,592
CASH AND CASH EQUIVALENTS, END OF YEAR	4,017,971	3,261,149	3,001,377
Cash paid during the year for:
Interest	233,139	418,840	253,026
Income taxes, net	116,412	158,296	85,872
Noncash investing and financing activities:
Loans transferred from held-for-investment to held-for-sale	329,069	285,637	481,593
Loans transferred from held-for-sale to held-for-investment	0	0	2,306
Loans transferred to other real estate owned (“OREO”)	$ 19,504	$ 2,013	$ 1,206