EARNINGS PER SHARE - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 25, 2020	Mar. 27, 2019
Numerator:
Net income (loss)	$ (1,079)	$ 3,607
Less: net income (loss) attributable to non-controlling interests	(119)	1,061
NET INCOME (LOSS) ATTRIBUTABLE TO SHAKE SHACK INC.	$ (960)	$ 2,546
Denominator:
Weighted-average shares of Class A common stock outstanding—basic (in shares)	34,444	29,563
Effect of dilutive securities:
Weighted-average shares of Class A common stock outstanding—diluted (in shares)	34,444	30,392
Earnings per share of Class A common stock—basic (in dollars per share)	$ (0.03)	$ 0.09
Earnings per share of Class A common stock—diluted (in dollars per share)	$ (0.03)	$ 0.08
Performance stock units
Effect of dilutive securities:
Stock options (in shares)	0	76
Restricted stock units
Effect of dilutive securities:
Stock options (in shares)	0	22
Stock options
Effect of dilutive securities:
Stock options (in shares)	0	731