Consolidated Statements of Financial Position (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Cash and cash equivalents:
Cash and cash due from banks	$ 121,796	$ 144,892	$ 122,288
Interest-bearing deposits with the Federal Reserve Bank and other banks	272,142	38,128	260,097
Total cash and cash equivalents	393,938	183,020	382,385
Investment securities:
Available-for-sale, at fair value	680,644	748,864	657,818
Held-to-maturity (fair value - $380,176 at March 31, 2015, $315,740 at December 31, 2014 and $272,407 at March 31, 2014)	381,450	316,413	278,099
Total investment securities	1,062,094	1,065,277	935,917
Loans held-for-sale, at fair value	9,675	9,128	3,814
Loans	5,702,874	5,688,230	4,753,289
Allowance for loan losses	(75,256)	(75,683)	(78,473)
Net loans	5,627,618	5,612,547	4,674,816
Premises and equipment (net of accumulated depreciation of $111,270 at March 31, 2015, $108,826 at December 31, 2014 and $102,163 at March 31, 2014)	96,486	97,496	74,779
Goodwill	180,128	180,128	120,164
Other intangible assets	31,655	33,080	12,872
Interest receivable and other assets	150,041	141,467	133,581
Total Assets	7,551,635	7,322,143	6,338,328
Deposits:
Noninterest-bearing	1,614,319	1,591,661	1,219,081
Interest-bearing	4,706,034	4,487,310	4,012,212
Total deposits	6,320,353	6,078,971	5,231,293
Interest payable and other liabilities	48,545	56,572	40,209
Short-term borrowings	372,236	389,467	361,231
Total liabilities	6,741,134	6,525,010	5,632,733
Shareholders’ equity:
Preferred stock, no par value: Authorized - 200,000 shares, none issued	0	0	0
Issued and outstanding — 32,847,063 shares at March 31, 2015, 32,774,420 shares at December 31, 2014 and 29,865,841 shares at March 31, 2014	32,847	32,774	29,866
Additional paid-in capital	565,851	565,166	489,045
Retained earnings	241,582	231,646	205,985
Accumulated other comprehensive loss	(29,779)	(32,453)	(19,301)
Total shareholders’ equity	810,501	797,133	705,595
Total Liabilities and Shareholders’ Equity	$ 7,551,635	$ 7,322,143	$ 6,338,328