STOCK-BASED COMPENSATION - Three Year Vest Restricted Shares (Details) - USD ($) $ / shares in Units, $ in Millions						6 Months Ended
	Feb. 24, 2020	Jan. 23, 2019	Jan. 24, 2018	Aug. 04, 2017	Jan. 25, 2017	Jun. 30, 2020
Shares
Outstanding (in shares)						188,870
Granted (in shares)						39,092
Vested (in shares)						(30,689)
Forfeited (in shares)						(200)
Outstanding (in shares)						197,073
Three-Year Vesting | Restricted Shares
Stock-based compensation
Vesting per year (as a percent)	33.33%	33.33%	33.33%		33.33%
Shares
Outstanding (in shares)						37,595
Granted (in shares)	19,451	20,696	17,712		17,451	19,451
Vested (in shares)						(18,054)
Forfeited (in shares)						(200)
Outstanding (in shares)						38,792
Weighted Average Fair Value
Outstanding (in dollars per share)						$ 60.21
Granted (in dollars per share)						59.70
Vested (in dollars per share)						59.69
Forfeited (in dollars per share)						58.78
Outstanding (in dollars per share)						$ 60.20
Compensation cost
Unrecognized compensation cost						$ 1.8
Weighted average period of recognition of unrecognized compensation cost						2 years
Equity Award Agreements | Three-Year Vesting
Award agreements
Period after change of control for equity award to fully vest upon termination of employment without cause or resignation				24 months