Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 288,066	$ 210,800
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	79,166	55,192
Accretion of discount and amortization of premiums, net	(13,348)	(29,960)
Stock-based compensation	10,115	9,210
Deferred tax expenses	3,699	4,357
Provision for credit losses	17,753	7,493
Net gains on sales of loans	(4,300)	(4,809)
Net gains on sales of available-for-sale investment securities	(5,194)	(6,678)
Net gains on sales of premises and equipment	(73,049)	(2,430)
Originations and purchases of loans held-for-sale	(9,806)	(3,364)
Proceeds from sales and paydowns/payoffs in loans held-for-sale	9,984	4,794
Net change in accrued interest receivable and other assets	94,552	(5,587)
Net change in accrued expenses and other liabilities	(14,986)	32,317
Other net operating activities	(2,399)	(32)
Total adjustments	92,187	60,503
Net cash provided by operating activities	380,253	271,303
Net (increase) decrease in:
Loans held-for-investment	(1,660,828)	(265,422)
Interest-bearing deposits with banks	31,060	65,113
Investments in qualified affordable housing partnerships, tax credit and other investments, net	(69,467)	(44,672)
Purchases of:
Resale agreements	(550,000)	(1,100,000)
Available-for-sale investment securities	(272,698)	(693,406)
Loans held-for-investment	(368,698)	(781,524)
Premises and equipment	(4,990)	(6,485)
Proceeds from sale of:
Available-for-sale investment securities	551,889	864,743
Loans held-for-investment	361,380	398,010
Other real estate owned (“OREO”)	5,298	1,351
Premises and equipment	116,021	7,276
Paydowns and maturities of resale agreements	950,000	1,050,000
Repayments, maturities and redemptions of available-for-sale investment securities	244,770	443,641
Other net investing activities	22,557	11,694
Net cash used in investing activities	(643,706)	(49,681)
Net increase (decrease) in:
Customer deposits	1,245,282	752,849
Short-term borrowings	(36,521)	30,064
Proceeds from:
Issuance of common stock pursuant to various stock compensation plans and agreements	1,008	1,062
Payments for:
Repayment of FHLB advances	0	(700,000)
Repayment of long-term debt	(10,000)	(10,000)
Repurchase of vested shares due to employee tax liability	(12,259)	(3,094)
Cash dividends on common stock	(58,949)	(58,152)
Other net financing activities	0	1,005
Net cash provided by financing activities	1,128,561	13,734
Effect of exchange rate changes on cash and cash equivalents	8,865	(3,447)
NET INCREASE IN CASH AND CASH EQUIVALENTS	873,973	231,909
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	1,878,503	1,360,887
CASH AND CASH EQUIVALENTS, END OF PERIOD	2,752,476	1,592,796
Cash paid during the period for:
Interest	63,416	50,044
Income tax payments, net	14,799	6,359
Noncash investing and financing activities:
Loans held-for-investment transferred to loans held-for-sale, net	343,977	575,804
Held-to-maturity investment security retained from securitization of loans	0	160,135
Unsettled purchases of available-for-sale investment securities	0	57,711
Unsettled purchases of loans receivable	$ 0	$ 106,114