Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities:
Net income	$ 166,111	$ 67,821	$ 100,656
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion	30,971	27,494	29,974
Provision for (release of) credit losses	9,500	3,800	(800)
Stock based compensation	6,057	5,827	4,496
Deferred income tax expense	32,630	99,562	59,727
Securities losses (gains), net	656	(42)	(982)
Gains from sales of government guaranteed loans	(9,277)	(10,493)	(9,545)
Net (gains) losses on sales and write downs of other assets	(152)	1,983	(397)
Net losses (gains) on sales and write downs of other real estate owned	283	791	(2)
Changes in assets and liabilities:
Decrease (increase) in other assets and accrued interest receivable	13,064	(18,299)	(39,007)
Increase in accrued expenses and other liabilities	3,772	24,280	1,299
Decrease (increase) in loans held for sale	16,391	5,238	(5,505)
Net cash provided by operating activities	270,006	207,962	139,914
Debt securities held-to-maturity:
Proceeds from maturities and calls	58,605	56,917	68,232
Purchases	(11,983)	(36,638)	(24,021)
Debt securities available-for-sale and equity securities:
Proceeds from sales	168,891	340,540	199,864
Proceeds from maturities and calls	346,505	605,889	392,575
Purchases	(566,333)	(936,947)	(692,983)
Net increase in loans	(291,890)	(109,433)	(657,650)
Net cash (paid) received for acquisitions	(56,800)	53,678	1,912
Purchase of bank owned life insurance	0	(10,000)	(20,000)
Purchases of premises and equipment	(17,617)	(22,183)	(17,375)
Proceeds from sales of premises and equipment	6,483	3,137	5,077
Proceeds from sale of other real estate owned	4,664	9,534	12,043
Net cash used in investing activities	(359,475)	(45,506)	(732,326)
Financing activities:
Net increase in deposits	727,839	287,073	365,531
Net (decrease) increase in short-term borrowings	(264,923)		(21,640)
Net (decrease) increase in short-term borrowings		43,859
Proceeds from Federal Home Loan Bank advances	2,860,000	4,000,000	9,780,000
Repayment of Federal Home Loan Bank advances	(3,204,003)	(4,294,000)	(9,514,125)
Repayment of long-term debt	(71,831)	(75,000)	0
Proceeds from issuance of long-term debt, net of issuance costs	98,188	0	0
Proceeds from issuance of common stock for dividend reinvestment and employee benefit plans	679	450	366
Proceeds from exercise of stock options	142	0	0
Cash paid for shares withheld to cover payroll taxes upon vesting of restricted stock	(1,998)	(1,701)	(1,189)
Repurchase of common stock	0	0	(13,659)
Retirement of preferred stock	0	0	(9,992)
Cash dividends on common stock	(41,634)	(26,210)	(15,849)
Cash dividends on preferred stock	0	0	(46)
Net cash provided by (used in) financing activities	102,459	(65,529)	569,397
Net change in cash and cash equivalents, including restricted cash	12,990	96,927	(23,015)
Cash and cash equivalents, including restricted cash, at beginning of year	314,275	217,348	240,363
Cash and cash equivalents, including restricted cash, at end of year	327,265	314,275	217,348
Cash paid during the period for:
Interest	56,830	34,657	32,141
Income taxes paid	$ 7,880	$ 6,514	$ 3,948