Summary of Significant Accounting Policies - Income (Loss) Per Share - Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Income (Loss) Per Share-Basic and Diluted
Net Income (Loss)	$ 152,254	$ 183,666	$ 187,263
Less: Net Income (Loss) Attributable to Noncontrolling Interests	7,663	3,510	3,029
Net Income (Loss) Attributable to Iron Mountain Incorporated	$ 144,591	$ 180,156	$ 184,234
Weighted-average shares—basic (in shares)	295,403,000	293,365,000	291,936,000
Effect of dilutive potential stock options (in shares)	1,946,000	2,241,000	1,435,000
Effect of dilutive potential RSUs and PUs (in shares)	467,000	628,000	594,000
Weighted-average shares—diluted (in shares)	297,816,000	296,234,000	293,965,000
Net Income (Loss) Per Share Attributable to Iron Mountain Incorporated:
Basic (in dollars per share)	$ 0.49	$ 0.61	$ 0.63
Diluted (in dollars per share)	$ 0.49	$ 0.61	$ 0.63
Antidilutive stock options, RSUs and PUs, excluded from the calculation (in shares)	113,130	225,847	81,817