EARNINGS PER SHARE - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 26, 2019	Jun. 27, 2018	Jun. 26, 2019	Jun. 27, 2018
Numerator:
Net income	$ 11,171	$ 10,571	$ 14,778	$ 15,550
Less: net income attributable to non-controlling interests	2,141	2,967	3,202	4,438
NET INCOME ATTRIBUTABLE TO SHAKE SHACK INC.	$ 9,030	$ 7,604	$ 11,576	$ 11,112
Denominator:
Weighted-average shares of Class A common stock outstanding—basic (in shares)	30,122	27,796	29,842	27,418
Effect of dilutive securities:
Weighted-average shares of Class A common stock outstanding—diluted (in shares)	31,015	28,754	30,703	28,288
Earnings per share of Class A common stock—basic (in dollars per share)	$ 0.30	$ 0.27	$ 0.39	$ 0.41
Earnings per share of Class A common stock—diluted (in dollars per share)	$ 0.29	$ 0.26	$ 0.38	$ 0.39
Performance stock units
Effect of dilutive securities:
Stock options (in shares)	68	68	72	68
Restricted stock units
Effect of dilutive securities:
Stock options (in shares)	50	23	36	17
Stock options
Effect of dilutive securities:
Stock options (in shares)	775	867	753	785