PARENT COMPANY FINANCIALS ONLY (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended									12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012
Condensed Financial Statements, Captions [Line Items]
Net income	$ 15,978		$ 15,738	$ 14,746	$ 13,383	$ 10,588	$ 14,655	$ 12,758	$ 12,252	$ 59,845		$ 50,254	$ 42,627
Adjustments to reconcile net income to net cash provided by operating activities
Deferred income tax expense (benefit)										2,840		2,557	(1,919)
Change in other assets										(6,617)		48,903	(1,575)
Change in other liabilities										7,258		(16,016)	4,408
Net cash provided by operating activities										84,739		141,335	43,952
Cash flows used in investing activities
Net cash used in investing activities										(287,106)		(208,596)	(267,939)
Cash flows provided by financing activities
Net repayments of short-term Federal Home Loan Bank borrowings										(65,000)		(50,000)
Proceeds from stock issued and stock options exercised										2,333		2,475	1,108
Issuance of shares under direct stock purchase plan										1,555		969	1,691
Common dividend paid										(22,443)		(15,122)	(22,494)
Net cash provided by financing activities										164,296		68,112	201,957
Net increase (decrease) in cash and cash equivalents										(38,071)		851	(22,030)
Cash and cash equivalents at beginning of year					216,325				215,474	216,325		215,474	237,504
Cash and cash equivalents at end of period	178,254					216,325				178,254		216,325	215,474
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Net income										59,845		50,254	42,627
Adjustments to reconcile net income to net cash provided by operating activities
Accretion										(486)		(155)	(13)
Deferred income tax expense (benefit)										293		203	(398)
Change in other assets												(373)	5,430
Change in other liabilities										25		206	(240)
Equity in undistributed income of subsidiaries										(22,545)		(22,305)	(16,000)
Net cash provided by operating activities										37,132		27,830	31,406
Cash flows used in investing activities
Cash paid for acquisitions, net of cash acquired												(10,832)	(21,648)
Net cash used in investing activities												(10,832)	(21,648)
Cash flows provided by financing activities
Proceeds from short-term borrowings												10,000	12,000
Repayment of short-term borrowings										(5,000)		(17,000)	(10,053)
Net repayments of short-term Federal Home Loan Bank borrowings										35,000
Proceeds from stock issued and stock options exercised										1,692		2,475	1,242
Issuance of shares under direct stock purchase plan										1,555		969	1,691
Common dividend paid										(22,443)		(15,122)	(22,494)
Net cash provided by financing activities										10,804		(18,678)	(17,614)
Net increase (decrease) in cash and cash equivalents										47,936		(1,680)	(7,856)
Cash and cash equivalents at beginning of year					16,855				18,535	16,855		18,535	26,391
Cash and cash equivalents at end of period	64,791					16,855				64,791		16,855	18,535
Cash	$ 64,791	[1]				$ 16,855				$ 64,791	[1]	$ 16,855

[1] Entire balance eliminates in consolidation.