REGULATORY MATTERS: (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013 Corporation 2013	Dec. 31, 2012 Corporation 2012	Dec. 31, 2013 First Financial Bank 2013	Dec. 31, 2012 First Financial Bank 2012
Capital [Abstract]
Capital	$ 375,601	$ 359,824	$ 349,968	$ 333,284
Capital to Risk Weighted Assets (percent)	17.13%	16.37%	16.49%	15.67%
Capital Required for Capital Adequacy	175,372	175,793	169,745	170,127
Capital Required for Capital Adequacy to Risk Weighted Assets (percent)	8.00%	8.00%	8.00%	8.00%
Capital Required to be Well Capitalized			212,181	212,659
Capital Required to be Well Capitalized to Risk Weighted Assets (percent)			10.00%	10.00%
Tier One Risk Based Capital [Abstract]
Tier One Risk Based Capital	355,533	337,866	332,644	314,303
Tier One Risk Based Capital to Risk Weighted Assets (percent)	16.22%	15.38%	15.68%	14.78%
Tier One Risk Based Capital Required for Capital Adequacy	87,686	87,897	84,872	85,064
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets (percent)	4.00%	4.00%	4.00%	4.00%
Tier One Risk Based Capital Required to be Well Capitalized			127,309	127,595
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets (percent)			6.00%	6.00%
Tier One Leverage Capital [Abstract]
Tier One Leverage Capital	355,533	337,866	332,644	314,303
Tier One Leverage Capital to Average Assets (percent)	11.69%	11.43%	11.40%	10.98%
Tier One Leverage Capital Required for Capital Adequacy	121,622	118,195	116,711	114,462
Tier One Leverage Capital Required for Capital Adequacy to Average Assets (percent)	4.00%	4.00%	4.00%	4.00%
Tier One Leverage Capital Required to be Well Capitalized			$ 145,889	$ 143,077
Tier One Leverage Capital Required to be Well Capitalized to Average Assets (percent)			5.00%	5.00%