Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income	$ 150,310	$ 137,752
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	38,707	16,575
Depreciation and amortization of premises and equipment	21,423	21,013
Amortization of tax credit investments	25,093	28,117
Net amortization of investment securities premiums	6,153	7,412
Investment securities gains, net	(37)	(7,139)
Gain on sales of mortgage loans held for sale	(10,158)	(10,122)
Proceeds from sales of mortgage loans held for sale	608,561	470,927
Originations of mortgage loans held for sale	(594,398)	(455,157)
Amortization of issuance costs and discounts on long-term debt	606	618
Stock-based compensation	6,007	3,339
Increase in accrued interest receivable	(5,674)	(3,788)
(Increase) decrease in other assets	(11,893)	9,991
Increase in accrued interest payable	1,834	936
Decrease in other liabilities	(3,843)	(4,943)
Total adjustments	82,381	77,779
Net cash provided by operating activities	232,691	215,531
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from sales of securities available for sale	54,638	44,485
Proceeds from principal repayments and maturities of securities held to maturity	15,475	0
Proceeds from principal repayments and maturities of securities available for sale	237,624	321,088
Purchase of securities available for sale	(459,799)	(344,569)
Increase in other interest-earning assets	(49,225)	(376,696)
Net increase in loans	(200,526)	(800,778)
Net change in tax credit investments	(29,857)	(24,758)
Net change in tax credit investments	47,096	21,084
Net cash used in investing activities	(478,766)	(1,202,312)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase in demand and savings deposits	342,080	1,014,697
Net increase in time deposits	109,402	114,219
Decrease in short-term borrowings	(131,959)	(242,566)
Additions to long-term debt	50,000	223,251
Repayments of long-term debt	(100,122)	(115,114)
Net proceeds from issuance of common stock	4,748	7,037
Dividends paid	(61,539)	(55,855)
Net cash provided by financing activities	212,610	945,669
Net Decrease in Cash and Restricted Cash	(33,465)	(41,112)
Cash and Restricted Cash at Beginning of Period	246,726	236,887
Cash and Restricted Cash at End of Period	213,261	195,775
Cash paid during the period for:
Interest	88,559	66,992
Income taxes	8,178	7,881
Supplemental schedule of certain noncash activities:
Transfer of student loans to loans held for sale	0	28,990
Transfer of available for sale securities to held to maturity securities	641,672	0
Restricted cash	$ 122,900	$ 96,000