Consolidated Statements of Cash Flow $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 66,170	$ 63,887	$ 54,317
Adjustments to reconcile to net cash provided by operating activities:
Provision for loan losses	7,675	3,072	1,258
Depreciation and amortization	11,901	11,349	11,077
Net amortization of securities premiums and discounts	1,020	910	1,563
Realized securities gains	(9,269)	(1,641)	(420)
Gain on sales of loans	(1,968)	(1,813)	(2,306)
Cash receipts from the sale of loans originated for sale	171,723	152,440	200,946
Cash disbursements for loans originated for sale	(174,047)	(153,592)	(193,853)
Deferred income tax benefit	(1,903)	(3,683)	(483)
Gain on other assets	(65)	(760)	(790)
(Increase)/decrease in interest receivable	(991)	(309)	284
Decrease in interest payable	(105)	(333)	(375)
Amortization of stock-based compensation arrangements	1,717	1,676	1,360
Other, net	6,301	5,719	5,512
Net cash provided by operating activities	78,159	76,922	78,090
INVESTING ACTIVITIES
Net cash and due from banks (paid for) received from acquisitions	(4,007)	174,283
Net decrease in federal funds sold	13,256	4,619	700
Purchases of held for investment securities	(1,771)	(708)	(902)
Purchases of available for sale securities	(91,136)	(224,217)	(157,139)
Proceeds from maturities, calls and paydowns of held for investment securities	2,103	4,101	5,816
Proceeds from maturities, calls and paydowns of available for sale securities	55,689	225,394	181,769
Proceeds from sales of available for sale securities	10,850	4,855	521
Net change in loans	(243,976)	(366,064)	(153,336)
Purchases of premises, equipment and computer software	(11,263)	(11,490)	(13,896)
Proceeds from the sale of other assets	4,957	5,851	5,389
Net cash used in investing activities	(265,298)	(183,376)	(131,078)
FINANCING ACTIVITIES
Net change in deposits	(106,422)	183,371	(21,311)
Net (decrease)/increase in short-term borrowings	(3,482)	(608)	19
Paydown of long-term borrowings		(6,938)	(2,240)
Issuance of common stock, net	4,428	6,532	5,200
Common stock acquired	(1,654)		(2,710)
Cash dividends paid	(21,449)	(19,543)	(13,583)
Net cash (used in) provided by financing activities	(128,579)	162,814	(34,625)
Net (decrease)/increase in cash, due from banks and interest-bearing deposits	(315,718)	56,360	(87,613)
Cash, due from banks and interest-bearing deposits at the beginning of the period	1,913,895	1,857,535	1,945,148
Cash, due from banks and interest-bearing deposits at the end of the period	1,598,177	1,913,895	1,857,535
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid during the period for interest	12,255	13,135	14,142
Cash paid during the period for income taxes	33,531	26,178	20,946
Noncash investing and financing activities:
Unpaid common stock dividends declared	$ 5,615	$ 5,265	$ 4,744