INCOME TAXES: (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Federal:
Currently payable	$ 7,886	$ 7,118	$ 7,018
Deferred	1,188	2,435	1,793
Federal income tax expense (benefit), continuing operations	9,074	9,553	8,811
State:
Currently payable	2,422	2,168	1,699
Deferred	196	406	635
State and local income tax expense (benefit), continuing operations	2,618	2,574	2,334
TOTAL	$ 11,692	$ 12,127	$ 11,145