Consolidated Statements of Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Interest income
Interest and fees on loans	$ 72,082	$ 62,287	$ 139,266	$ 121,080
Interest Income, Securities, Operating, Taxable	6,498	5,609	12,717	10,976
Nontaxable interest and dividends on securities	16	26	32	52
Interest on loans held for sale	30	21	49	35
Interest on federal funds sold and short-term investments	541	190	852	397
Total interest and dividend income	79,167	68,133	152,916	132,540
Interest expense
Interest on deposits	4,587	2,912	8,522	5,679
Interest on borrowings	1,412	1,466	2,755	2,906
Total interest expense	5,999	4,378	11,277	8,585
Net interest income	73,168	63,755	141,639	123,955
Provision for loan losses	2,000	1,050	2,500	1,650
Net interest income after provision for loan losses	71,168	62,705	139,139	122,305
Noninterest income
Deposit account fees	4,551	4,392	8,982	8,936
Interchange and ATM fees	4,769	4,434	8,942	8,356
Investment management	6,822	5,995	12,964	11,609
Mortgage banking income	1,038	1,314	1,908	2,271
Available-For-Sale- Securities - Equity - Gross Realized Gains	2	3	2	7
Increase in cash surrender value of life insurance policies	998	1,017	1,945	1,981
Loan level derivative income	708	1,337	1,155	1,943
Other noninterest income	2,999	2,906	5,852	5,207
Total noninterest income	21,887	21,398	41,750	40,310
Noninterest expenses
Salaries and employee benefits	30,288	28,654	61,388	56,978
Occupancy and equipment expenses	6,497	6,059	13,905	12,217
Data processing & facilities management	1,264	1,188	2,550	2,460
FDIC assessment	691	778	1,489	1,561
Advertising expense	1,166	1,365	2,289	2,659
Professional Fees	1,089	1,262	1,845	1,816
Debit Card Expense	841	852	1,650	1,624
Available-For-Sale Securities - Equity Gross Realized Losses	0	2	0	5
Business Combination, Acquisition Related Costs	434	2,909	434	3,393
Software Maintenance	997	896	1,969	1,826
Other noninterest expenses	9,421	8,844	18,620	17,043
Total noninterest expenses	52,688	52,809	106,139	101,582
Income before income taxes	40,367	31,294	74,750	61,033
Provision for income taxes	9,249	10,731	16,077	19,745
Net income	$ 31,118	$ 20,563	$ 58,673	$ 41,288
Basic earnings per share (in dollars per share)	$ 1.13	$ 0.75	$ 2.13	$ 1.52
Diluted earnings per share (in dollars per share)	$ 1.13	$ 0.75	$ 2.13	$ 1.52
Weighted average common shares (basic) (in shares)	27,526,653	27,257,799	27,506,724	27,144,350
Common shares equivalents (in shares)	54,525	74,497	61,480	78,757
Weighted average common shares (diluted) (in shares)	27,581,178	27,332,296	27,568,204	27,223,107
Retained Earnings [Member]
Noninterest expenses
Net income			$ 58,673	$ 41,288
Cash dividends declared per common share (in dollars per share)	$ 0.38	$ 0.32	$ 0.76	$ 0.64