NON-CONTROLLING INTERESTS - Ownership Interest in SSE Holdings (Details) - shares	Jun. 30, 2021	Dec. 30, 2020
Noncontrolling Interest [Line Items]
Number of LLC Interests held by Shake Shack Inc. (in shares)	39,134,356	38,717,790
Number of LLC Interests held by non-controlling interest holders (in shares)	2,921,587	2,951,188
Total LLC Interests outstanding (in shares)	42,055,943	41,668,978
Total LLC Interests outstanding (as a percentage)	100.00%	100.00%
Shake Shack Inc.
Noncontrolling Interest [Line Items]
Number of LLC Interests held by Shake Shack Inc. (as a percentage)	93.10%	92.90%
Non-Controlling Interest Holders
Noncontrolling Interest [Line Items]
Number of LLC Interests held by non-controlling interest holders (as a percentage)	6.90%	7.10%