CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Thousands	Total	Class A Common Stock	Class B Common Stock	Common Stock [Member] Class A Common Stock	Common Stock [Member] Class B Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Non- Controlling Interest
Beginning balance (shares) at Dec. 25, 2019				34,417,302	3,145,197
Beginning balance at Dec. 25, 2019	$ 321,985			$ 35	$ 3	$ 244,410	$ 54,367	$ 2	$ 23,168
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) attributable to Shake Shack Inc.—basic	(1,079)						(960)		(119)
Other comprehensive income (loss):
Net change in foreign currency translation adjustment	1							1
Equity-based compensation	1,313					1,313
Activity under stock compensation plans (in shares)				77,903
Activity under stock compensation plans	63					424			(361)
Redemption of LLC Interests (in shares)				28,195	28,195
Stock Issued During Period, Value, Conversion of Units	0			$ 0	$ 0	195			195
Establishment of liabilities under tax receivable agreement and related changes to deferred tax assets associated with increases in tax basis	628					628
Distributions paid to non-controlling interest holders	(305)								(305)
Ending balance (shares) at Mar. 25, 2020				34,523,400	3,117,002
Ending balance at Mar. 25, 2020	322,606			$ 35	$ 3	246,970	53,407	3	22,188
Beginning balance (shares) at Dec. 30, 2020		38,717,790	2,951,188	38,717,790	2,951,188
Beginning balance at Dec. 30, 2020	434,493			$ 39	$ 3	395,067	12,209	3	27,172
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) attributable to Shake Shack Inc.—basic	575						1,309		(734)
Other comprehensive income (loss):
Net change in foreign currency translation adjustment	(1)							(1)
Equity-based compensation	1,696					1,696
Activity under stock compensation plans (in shares)				355,849
Activity under stock compensation plans	3,441					3,359			82
Redemption of LLC Interests (in shares)				29,600	29,600
Stock Issued During Period, Value, Conversion of Units	0					36			36
Establishment of liabilities under tax receivable agreement and related changes to deferred tax assets associated with increases in tax basis	213					213
Distributions paid to non-controlling interest holders	(467)								(467)
Ending balance (shares) at Mar. 31, 2021		39,103,239	2,921,588	39,103,239	2,921,588
Ending balance at Mar. 31, 2021	$ 439,950			$ 39	$ 3	$ 400,371	$ 13,518	$ 2	$ 26,017