PARENT COMPANY CONDENSED FINANCIAL STATEMENTS: (Details 2) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income	$ 8,344	$ 8,162	$ 8,232	$ 13,675	$ 7,114	$ 8,398	$ 6,923	$ 7,761	$ 38,413	$ 30,196	$ 33,772
Adjustments to reconcile net income to net cash provided by operating activities:
Contribution of shares to ESOP									1,361	1,294	1,253
CASH FLOWS FROM FINANCING ACTIVITIES:
Purchases of treasury stock									(19,396)	(8,698)	(14,633)
Dividends paid									(12,359)	(12,632)	(12,949)
NET CHANGE IN CASH AND CASH EQUIVALENTS									(13,683)	10,593	7,069
CASH AND DUE FROM BANKS, BEGINNING OF YEAR				88,695				78,102	88,695	78,102	71,033
CASH AND DUE FROM BANKS, END OF YEAR	75,012				88,695				75,012	88,695	78,102
Supplemental disclosures of cash flow information:
Interest									4,432	4,237	5,527
Income Taxes									18,739	12,869	9,354
Parent
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income									38,413	30,196	33,772
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization									200	203	196
Equity in undistributed earnings									(7,670)	(11,503)	(8,109)
Contribution of shares to ESOP									1,361	1,294	1,253
Restricted stock compensation									684	684	1,072
Increase (decrease) in other liabilities									(262)	(1,524)	(473)
(Increase) decrease in other assets									12	188	155
NET CASH FROM OPERATING ACTIVITIES									32,738	19,538	27,866
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of furniture and fixtures									0	(65)	(1,299)
NET CASH FROM INVESTING ACTIVITIES									0	(65)	(1,299)
CASH FLOWS FROM FINANCING ACTIVITIES:
Purchases of treasury stock									(19,396)	(8,698)	(14,633)
Dividends paid									(12,359)	(12,632)	(12,949)
NET CASH FROM FINANCING ACTIVITES									(31,755)	(21,330)	(27,582)
NET CHANGE IN CASH AND CASH EQUIVALENTS									983	(1,857)	(1,015)
CASH AND DUE FROM BANKS, BEGINNING OF YEAR				$ 1,782				$ 3,639	1,782	3,639	4,654
CASH AND DUE FROM BANKS, END OF YEAR	$ 2,765				$ 1,782				2,765	1,782	3,639
Supplemental disclosures of cash flow information:
Interest									0	0	0
Income Taxes									$ 18,739	$ 12,869	$ 9,354