Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income	$ 84,677	$ 88,847
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	37,087	11,500
Depreciation and amortization of premises and equipment	14,580	13,974
Amortization of tax credit investments	16,729	17,932
Net amortization of investment securities premiums	4,856	4,775
Investment securities gains, net	(23)	(2,542)
Gain on sales of mortgage loans held for sale	(6,499)	(6,562)
Proceeds from sales of mortgage loans held for sale	379,399	283,251
Originations of mortgage loans held for sale	(377,268)	(281,356)
Amortization of issuance costs on long-term debt	399	382
Stock-based compensation	4,184	1,769
Increase in accrued interest receivable	(2,298)	(1,309)
Increase in other assets	(10,687)	(44,542)
Decrease in accrued interest payable	(1,024)	(1,828)
(Decrease) increase in other liabilities	(9,278)	3,398
Total adjustments	50,157	(1,158)
Net cash provided by operating activities	134,834	87,689
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from sales of securities available for sale	48,731	29,518
Proceeds from principal repayments and maturities of securities available for sale	170,141	225,788
Purchase of securities available for sale	(306,713)	(158,078)
Increase in other interest-earning assets	(3,480)	(71,845)
Net increase in loans	(65,361)	(655,172)
Net change in tax credit investments	(21,973)	(13,726)
Net change in tax credit investments	38,544	12,725
Net cash used in investing activities	(217,199)	(656,240)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net (decrease) increase in demand and savings deposits	(265,298)	351,329
Net increase (decrease) in time deposits	67,565	(6,832)
Increase in short-term borrowings	366,309	153,542
Additions to long-term debt	50,000	223,251
Repayments of long-term debt	(100,081)	(115,075)
Net proceeds from issuance of common stock	2,455	4,870
Dividends paid	(40,378)	(36,614)
Net cash provided by financing activities	80,572	574,471
Net (Decrease) Increase in Cash and Restricted Cash	(1,793)	5,920
Cash and Restricted Cash at Beginning of Period	246,726	236,887
Cash and Restricted Cash at End of Period	244,933	242,807
Cash paid during the period for:
Interest	57,496	45,054
Income taxes	5,794	7,016
Supplemental schedule of certain noncash activities:
Transfer of student loans to loans held for sale	0	28,990
Restricted cash	$ 145,200	$ 147,900