Iron Mountain (IRM) 10-Q 6 Nov 24 2024 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2024	Nov. 01, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2024
Document Transition Report	false
Entity File Number	1-13045
Entity Registrant Name	IRON MOUNTAIN INC
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	23-2588479
Entity Address, Address Line One	85 New Hampshire Avenue
Entity Address, Address Line Two	Suite 150
Entity Address, City or Town	Portsmouth
Entity Address, State or Province	NH
Entity Address, Postal Zip Code	03801
City Area Code	617
Local Phone Number	535-4766
Title of 12(b) Security	Common Stock, $.01 par value
Trading Symbol	IRM
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Emerging Growth Company	false
Small Business Entity	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		293,460,371
Entity Central Index Key	0001020569
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Amendment Flag	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Current Assets:
Cash and cash equivalents	$ 168,515	$ 222,789
Accounts receivable (less allowances of $84,190 and $74,762 as of September 30, 2024 and December 31, 2023, respectively)	1,243,464	1,259,826
Prepaid expenses and other	306,867	252,930
Total Current Assets	1,718,846	1,735,545
Property, Plant and Equipment:
Property, plant and equipment	11,549,081	10,373,989
Less—Accumulated depreciation	(4,354,477)	(4,059,120)
Property, Plant and Equipment, Net	7,194,604	6,314,869
Other Assets, Net:
Goodwill	5,198,460	5,017,912
Customer and supplier relationships and other intangible assets	1,276,963	1,279,800
Operating lease right-of-use assets	2,591,238	2,696,024
Other	489,518	429,652
Total Other Assets, Net	9,556,179	9,423,388
Total Assets	18,469,629	17,473,802
Current Liabilities:
Current portion of long-term debt	136,547	120,670
Accounts payable	586,793	539,594
Accrued expenses and other current liabilities (includes current portion of operating lease liabilities)	1,288,176	1,250,259
Deferred revenue	294,545	325,665
Total Current Liabilities	2,306,061	2,236,188
Long-term Debt, net of current portion	13,245,462	11,812,500
Long-term Operating Lease Liabilities, net of current portion	2,438,905	2,562,394
Other Long-term Liabilities	277,588	237,590
Deferred Income Taxes	233,484	235,410
Commitments and Contingencies
Redeemable Noncontrolling Interests	70,537	177,947
Iron Mountain Incorporated Stockholders' (Deficit) Equity:
Preferred stock (par value $0.01; authorized 10,000,000 shares; none issued and outstanding)	0	0
Common stock (par value $0.01; authorized 400,000,000 shares; issued and outstanding 293,425,265 and 292,142,739 shares as of September 30, 2024 and December 31, 2023, respectively)	2,934	2,921
Additional paid-in capital	4,602,246	4,533,691
(Distributions in excess of earnings) Earnings in excess of distributions	(4,475,682)	(3,953,808)
Accumulated other comprehensive items, net	(388,511)	(371,156)
Total Iron Mountain Incorporated Stockholders' (Deficit) Equity	(259,013)	211,648
Noncontrolling Interests	156,605	125
Total (Deficit) Equity	(102,408)	211,773
Total Liabilities and (Deficit) Equity	$ 18,469,629	$ 17,473,802

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 84,190	$ 74,762
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, authorized shares (in shares)	10,000,000	10,000,000
Preferred stock, issued shares (in shares)	0	0
Preferred stock, outstanding shares (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized shares (in shares)	400,000,000	400,000,000
Common stock, issued shares (in shares)	293,425,265	292,142,739
Common stock, outstanding shares (in shares)	293,425,265	292,142,739

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Revenues:
Total Revenues	$ 1,557,358	$ 1,388,175	$ 4,568,630	$ 4,060,460
Operating Expenses:
Cost of sales (excluding depreciation and amortization)	678,390	592,201	2,007,616	1,756,471
Selling, general and administrative	341,929	315,030	1,006,232	921,355
Depreciation and amortization	232,240	198,757	666,296	576,218
Acquisition and Integration Costs	11,262	9,909	28,573	13,015
Restructuring and other transformation	37,282	38,861	124,562	121,362
Loss (gain) on disposal/write-down of property, plant and equipment, net	5,091	(4,416)	8,270	(18,982)
Total Operating Expenses	1,306,194	1,150,342	3,841,549	3,369,439
Operating Income (Loss)	251,164	237,833	727,081	691,021
Interest expense, net	186,067	152,801	527,107	434,148
Other Expense (Income), Net	86,362	(16,271)	79,665	67,879
Net Income (Loss) Before Provision (Benefit) for Income Taxes	(21,265)	101,303	120,309	188,994
Provision (Benefit) for Income Taxes	12,400	9,912	42,328	30,925
Net Income (Loss)	(33,665)	91,391	77,981	158,069
Less: Net Income (Loss) Attributable to Noncontrolling Interests	(45)	348	1,757	2,317
Net Income (Loss) Attributable to Iron Mountain Incorporated	$ (33,620)	$ 91,043	$ 76,224	$ 155,752
Net Income (Loss) Per Share Attributable to Iron Mountain Incorporated:
Basic (in dollars per share)	$ (0.11)	$ 0.31	$ 0.26	$ 0.53
Diluted (in dollars per share)	$ (0.11)	$ 0.31	$ 0.26	$ 0.53
Weighted average common shares outstanding-basic (in shares)	293,603,000	292,148,000	293,229,000	291,805,000
Weighted average common shares outstanding-diluted (in shares)	293,603,000	294,269,000	295,912,000	293,615,000
Storage rental
Revenues:
Total Revenues	$ 935,701	$ 858,656	$ 2,740,289	$ 2,499,501
Service
Revenues:
Total Revenues	$ 621,657	$ 529,519	$ 1,828,341	$ 1,560,959

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Income Statement [Abstract]
Interest income	$ 949	$ 4,059	$ 4,374	$ 9,256

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Statement of Comprehensive Income [Abstract]
Net (Loss) Income	$ (33,665)	$ 91,391	$ 77,981	$ 158,069
Other Comprehensive Income (Loss):
Foreign Currency Translation Adjustment	107,282	(80,168)	8,434	(21,907)
Change in Fair Value of Derivative Instruments	(34,281)	6,184	(23,381)	10,638
Reclassifications from Accumulated Other Comprehensive Items, net	0	(2,527)	(2,528)	(5,054)
Total Other Comprehensive Income (Loss):	73,001	(76,511)	(17,475)	(16,323)
Comprehensive Income (Loss)	39,336	14,880	60,506	141,746
Comprehensive Income (Loss) Attributable to Noncontrolling Interests	376	(404)	1,637	1,994
Comprehensive Income (Loss) Attributable to Iron Mountain Incorporated	$ 38,960	$ 15,284	$ 58,869	$ 139,752

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF (DEFICIT) EQUITY - USD ($) $ in Thousands	Total	COMMON STOCK	ADDITIONAL PAID-IN CAPITAL	(DISTRIBUTIONS IN EXCESS OF EARNINGS) EARNINGS IN EXCESS OF DISTRIBUTIONS	ACCUMULATED OTHER COMPREHENSIVE ITEMS, NET	NONCONTROLLING INTERESTS	REDEEMABLE NONCONTROLLING INTERESTS
Beginning of Period at Dec. 31, 2022	$ 636,793	$ 2,908	$ 4,468,035	$ (3,392,272)	$ (442,003)	$ 125
Beginning balance (in shares) at Dec. 31, 2022		290,830,296
Increase (Decrease) in Stockholders' Equity
Issuance and net settlement of shares under employee stock purchase and option plans and stock-based compensation	39,393	$ 11	39,382
Issuance and net settlement of shares under employee stock purchase plan and option plans and stock-based compensation (in shares)		1,097,111
Changes in equity related to redeemable noncontrolling interests	967		967				$ (1,367)
Parent cash dividends declared	(554,274)			(554,274)
Other comprehensive Income (loss)	(16,000)				(16,000)
Net (loss) income	155,752			155,752
End of Period at Sep. 30, 2023	262,631	$ 2,919	4,508,384	(3,790,794)	(458,003)	125
Ending balance (in shares) at Sep. 30, 2023		291,927,407
Beginning of redeemable noncontrolling interest at Dec. 31, 2022							95,160
Increase (Decrease) in Temporary Equity [Roll Forward]
Changes in equity related to redeemable noncontrolling interests	967		967				(1,367)
Other comprehensive Income (loss)							(323)
Net income (loss)							2,317
Noncontrolling interests equity contributions							9,900
Noncontrolling interests dividends							(2,937)
Purchase of noncontrolling interests							60,520
Ending of redeemable noncontrolling interest at Sep. 30, 2023							163,270
Beginning of Period at Jun. 30, 2023	416,343	$ 2,918	4,488,492	(3,692,948)	(382,244)	125
Beginning balance (in shares) at Jun. 30, 2023		291,824,958
Increase (Decrease) in Stockholders' Equity
Issuance and net settlement of shares under employee stock purchase and option plans and stock-based compensation	20,293	$ 1	20,292
Issuance and net settlement of shares under employee stock purchase plan and option plans and stock-based compensation (in shares)		102,449
Changes in equity related to redeemable noncontrolling interests	(400)		(400)
Parent cash dividends declared	(188,889)			(188,889)
Other comprehensive Income (loss)	(75,759)				(75,759)
Net (loss) income	91,043			91,043
End of Period at Sep. 30, 2023	262,631	$ 2,919	4,508,384	(3,790,794)	(458,003)	125
Ending balance (in shares) at Sep. 30, 2023		291,927,407
Beginning of redeemable noncontrolling interest at Jun. 30, 2023							104,059
Increase (Decrease) in Temporary Equity [Roll Forward]
Changes in equity related to redeemable noncontrolling interests	(400)		(400)
Other comprehensive Income (loss)							(752)
Net income (loss)							348
Noncontrolling interests dividends							(905)
Purchase of noncontrolling interests							60,520
Ending of redeemable noncontrolling interest at Sep. 30, 2023							163,270
Beginning of Period at Dec. 31, 2023	$ 211,773	$ 2,921	4,533,691	(3,953,808)	(371,156)	125
Beginning balance (in shares) at Dec. 31, 2023	292,142,739	292,142,739
Increase (Decrease) in Stockholders' Equity
Issuance and net settlement of shares under employee stock purchase and option plans and stock-based compensation	$ 54,710	$ 13	54,697
Issuance and net settlement of shares under employee stock purchase plan and option plans and stock-based compensation (in shares)		1,282,526
Changes in equity related to redeemable noncontrolling interests	(614)		(54,024)			53,410	(107,102)
Parent cash dividends declared	(598,098)			(598,098)
Other comprehensive Income (loss)	(17,355)				(17,355)
Net (loss) income	76,224			76,224
Noncontrolling Interest, Equity Contributions And Related Costs	170,952		67,882			103,070
End of Period at Sep. 30, 2024	$ (102,408)	$ 2,934	4,602,246	(4,475,682)	(388,511)	156,605
Ending balance (in shares) at Sep. 30, 2024	293,425,265	293,425,265
Beginning of redeemable noncontrolling interest at Dec. 31, 2023	$ 177,947						177,947
Increase (Decrease) in Temporary Equity [Roll Forward]
Changes in equity related to redeemable noncontrolling interests	(614)		(54,024)			53,410	(107,102)
Other comprehensive Income (loss)							(120)
Net income (loss)							1,757
Noncontrolling interests dividends							(1,945)
Ending of redeemable noncontrolling interest at Sep. 30, 2024	70,537						70,537
Beginning of Period at Jun. 30, 2024	(132,749)	$ 2,933	4,555,883	(4,230,599)	(461,091)	125
Beginning balance (in shares) at Jun. 30, 2024		293,298,465
Increase (Decrease) in Stockholders' Equity
Issuance and net settlement of shares under employee stock purchase and option plans and stock-based compensation	32,928	$ 1	32,927
Issuance and net settlement of shares under employee stock purchase plan and option plans and stock-based compensation (in shares)		126,800
Changes in equity related to redeemable noncontrolling interests	(1,036)		(54,446)			53,410	(113,964)
Parent cash dividends declared	(211,463)			(211,463)
Other comprehensive Income (loss)	72,580				72,580
Net (loss) income	(33,620)			(33,620)
Noncontrolling Interest, Equity Contributions And Related Costs	170,952		67,882			103,070
End of Period at Sep. 30, 2024	$ (102,408)	$ 2,934	4,602,246	$ (4,475,682)	$ (388,511)	156,605
Ending balance (in shares) at Sep. 30, 2024	293,425,265	293,425,265
Beginning of redeemable noncontrolling interest at Jun. 30, 2024							184,861
Increase (Decrease) in Temporary Equity [Roll Forward]
Changes in equity related to redeemable noncontrolling interests	$ (1,036)		$ (54,446)			$ 53,410	(113,964)
Other comprehensive Income (loss)							421
Net income (loss)							(45)
Noncontrolling interests dividends							(736)
Ending of redeemable noncontrolling interest at Sep. 30, 2024	$ 70,537						$ 70,537

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Cash Flows from Operating Activities:
Net income (loss)	$ 77,981	$ 158,069
Adjustments to reconcile net income (loss) to cash flows from operating activities:
Depreciation	466,905	387,327
Amortization (includes amortization of deferred financing costs and discounts of [$18,909] and $13,580 for the nine months ended September 30, 2024 and 2023, respectively)	218,300	202,471
Revenue reduction associated with amortization of customer inducements and above- and below-market leases	4,117	5,206
Stock-based compensation expense	73,491	53,195
(Benefit) provision for deferred income taxes	(9,012)	(7,727)
Loss on early extinguishment of debt	5,417	0
Loss (gain) on disposal/write-down of property, plant and equipment, net	8,270	(18,982)
Loss associated with the Clutter Acquisition	0	38,000
Foreign currency transactions and other, net	100,436	55,768
(Increase) decrease in assets	(45,677)	(6,889)
(Decrease) increase in liabilities	(135,100)	(200,064)
Cash Flows from Operating Activities	765,128	666,374
Cash Flows from Investing Activities:
Capital expenditures	(1,173,968)	(962,294)
Cash paid for acquisitions, net of cash acquired	(174,445)	(33,932)
Acquisition of customer intangibles	(5,820)	(5,799)
Contract costs	(84,112)	(61,960)
Investments in joint ventures and other investments, net	(9,834)	(15,830)
Proceeds from sales of property and equipment and other, net	6,350	44,732
Cash Flows from Investing Activities	(1,441,829)	(1,035,083)
Cash Flows from Financing Activities:
Repayment of revolving credit facility, term loan facilities and other debt	(8,974,574)	(13,654,869)
Proceeds from revolving credit facility, term loan facilities and other debt	10,247,884	13,630,522
Net proceeds from sale of senior note	0	990,000
Debt financing and equity contribution from noncontrolling interests	178,616	9,900
Equity distribution to noncontrolling interests	(1,945)	(2,937)
Repurchase of noncontrolling interest	(35,203)	0
Parent cash dividends	(579,494)	(547,667)
Payment of deferred purchase obligation	(158,677)	0
Net (payments) proceeds associated with employee stock-based awards	(18,781)	(13,802)
Other, net	(18,625)	(7,275)
Cash Flows from Financing Activities	639,201	403,872
Effect of Exchange Rates on Cash and Cash Equivalents	(16,774)	(6,458)
(Decrease) Increase in Cash and Cash Equivalents	(54,274)	28,705
Cash and Cash Equivalents, Beginning of Period	222,789	141,797
Cash and Cash Equivalents, End of Period	168,515	170,502
Supplemental Information:
Cash Paid for Interest	644,301	470,273
Cash Paid for Income Taxes, Net	68,135	74,948
Non-Cash Investing and Financing Activities:
Financing Leases and Other	129,109	104,613
Accrued Capital Expenditures	241,240	176,596
Deferred Purchase Obligations and Other Deferred Payments	260,813	4,786
Dividends Payable	$ 220,996	$ 200,879

CONDENSED CONSOLIDATED STATEM_6

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Statement of Cash Flows [Abstract]
Deferred financing costs and discount included in amortization	$ 18,909	$ 13,580

General

General	9 Months Ended
	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
General	GENERAL The unaudited condensed consolidated financial statements of Iron Mountain Incorporated, a Delaware corporation, and its subsidiaries ("we" or "us"), have been prepared pursuant to the rules and regulations of the United States Securities and Exchange Commission (the "SEC"). Certain information and footnote disclosures normally included in the annual financial statements prepared in accordance with accounting principles generally accepted in the United States of America have been omitted pursuant to those rules and regulations, but we believe that the disclosures included herein are adequate to make the information presented not misleading. The interim condensed consolidated financial statements are presented herein and, in the opinion of management, reflect all adjustments of a normal recurring nature necessary for a fair presentation. Interim results are not necessarily indicative of results for a full year. The Condensed Consolidated Financial Statements and Notes thereto, which are included herein, should be read in conjunction with the Consolidated Financial Statements and Notes thereto for the year ended December 31, 2023 included in our Annual Report on Form 10-K filed with the SEC on February 22, 2024 (our "Annual Report"). In September 2022, we announced a global program designed to accelerate the growth of our business ("Project Matterhorn"). See Note 11.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2024
Accounting Policies [Abstract]
Summary Of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES A. CASH AND CASH EQUIVALENTS Cash and cash equivalents include cash on hand and cash invested in highly liquid short-term securities, which have remaining maturities at the date of purchase of less than 90 days. Cash and cash equivalents are carried at cost, which approximates fair value. B. ACCOUNTS RECEIVABLE We maintain an allowance for doubtful accounts and a credit memo reserve for estimated losses resulting from the potential inability of our customers to make required payments and potential disputes regarding billing and service issues. The rollforward of the allowance for doubtful accounts and credit memo reserves for the nine months ended September 30, 2024 is as follows: Balance as of December 31, 2023 $ 74,762 Credit memos charged to revenue 73,762 Allowance for bad debts charged to expense 37,668 Deductions and other (1) (102,002) Balance as of September 30, 2024 $ 84,190 (1) Primarily consists of the issuance of credit memos, the write-off of accounts receivable and the impact associated with currency translation adjustments. C. LEASES We lease facilities for certain warehouses, data centers and office space. We also have land leases, including those on which certain facilities are located. Operating and financing lease right-of-use assets and lease liabilities as of September 30, 2024 and December 31, 2023 are as follows: DESCRIPTION SEPTEMBER 30, 2024 DECEMBER 31, 2023 Assets: Operating lease right-of-use assets $ 2,591,238 $ 2,696,024 Financing lease right-of-use assets, net of accumulated depreciation (1) 367,500 304,600 Liabilities: Current Operating lease liabilities $ 315,093 $ 291,795 Financing lease liabilities (1) 50,455 39,089 Long-term Operating lease liabilities $ 2,438,905 $ 2,562,394 Financing lease liabilities (1) 363,155 310,776 (1) Financing lease right-of-use assets, current financing lease liabilities and long-term financing lease liabilities are included within Property, plant and equipment, net, Current portion of long-term debt and Long-term debt, net of current portion, respectively, within our Condensed Consolidated Balance Sheets. The components of the lease expense for the three and nine months ended September 30, 2024 and 2023 are as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, DESCRIPTION 2024 2023 2024 2023 Operating lease cost (1) $ 168,308 $ 172,040 $ 512,789 $ 489,153 Financing lease cost: Depreciation of financing lease right-of-use assets $ 13,907 $ 11,004 $ 36,929 $ 31,214 Interest expense for financing lease liabilities 5,593 4,843 16,031 13,600 (1) Operating lease cost, the majority of which is included in Cost of sales, includes variable lease costs of $42,785 and $120,473 for the three and nine months ended September 30, 2024, respectively, and $34,866 and $100,864 for the three and nine months ended September 30, 2023, respectively. Other information: Supplemental cash flow information relating to our leases for the nine months ended September 30, 2024 and 2023 is as follows: NINE MONTHS ENDED SEPTEMBER 30, CASH PAID FOR AMOUNTS INCLUDED IN MEASUREMENT OF LEASE LIABILITIES: 2024 2023 Operating cash flows used in operating leases $ 355,509 $ 334,806 Operating cash flows used in financing leases (interest) 16,031 13,600 Financing cash flows used in financing leases 41,079 35,124 NON-CASH ITEMS: Operating lease modifications and reassessments $ 9,536 $ 65,874 New operating leases (including acquisitions and sale-leaseback transactions) 97,708 234,194 D. GOODWILL Our reporting units as of December 31, 2023 are described in detail in Note 2.l. to Notes to Consolidated Financial Statements included in our Annual Report. The changes in the carrying value of goodwill attributable to each reportable segment and Corporate and Other (as defined in Note 9) for the nine months ended September 30, 2024 are as follows: GLOBAL RIM BUSINESS GLOBAL DATA CENTER BUSINESS CORPORATE AND OTHER TOTAL CONSOLIDATED Goodwill balance, net of accumulated amortization, as of December 31, 2023 $ 3,911,945 $ 478,930 $ 627,037 $ 5,017,912 Tax deductible goodwill acquired during the period — — 131,790 131,790 Non-tax deductible goodwill acquired during the period — — 36,499 36,499 Fair value and other adjustments 984 (186) (186) 612 Currency effects 9,686 1,062 899 11,647 Goodwill balance, net of accumulated amortization, as of September 30, 2024 $ 3,922,615 $ 479,806 $ 796,039 $ 5,198,460 Accumulated goodwill impairment balance as of September 30, 2024 $ 132,409 $ — $ 26,011 $ 158,420 E. FAIR VALUE MEASUREMENTS The assets and liabilities carried at fair value measured on a recurring basis as of September 30, 2024 and December 31, 2023 are as follows: FAIR VALUE MEASUREMENTS AT SEPTEMBER 30, 2024 USING DESCRIPTION TOTAL CARRYING VALUE AT SEPTEMBER 30, 2024 QUOTED PRICES IN SIGNIFICANT OTHER SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3) (2) Money Market Funds $ 17,581 $ — $ 17,581 $ — Time Deposits 30,462 — 30,462 — Trading Securities 8,013 6,283 1,730 — Derivative Liabilities 29,824 — 29,824 — Deferred Purchase Obligations (1) 117,050 — — 117,050 FAIR VALUE MEASUREMENTS AT DECEMBER 31, 2023 USING DESCRIPTION TOTAL CARRYING VALUE AT DECEMBER 31, 2023 QUOTED PRICES IN SIGNIFICANT OTHER SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3) (2) Money Market Funds $ 66,008 $ — $ 66,008 $ — Time Deposits 15,913 — 15,913 — Trading Securities 9,952 6,149 3,803 — Derivative Assets 6,359 — 6,359 — Derivative Liabilities 5,769 — 5,769 — Deferred Purchase Obligations (1) 208,265 — — 208,265 (1) Primarily relates to the fair values of the deferred purchase obligations associated with the ITRenew Transaction (as defined in Note 3 to Notes to Consolidated Financial Statements included in our Annual Report) and the Regency Transaction (as defined in Note 3). (2) The following is a rollforward of the Level 3 liabilities presented above for December 31, 2023 through September 30, 2024: Balance as of December 31, 2023 $ 208,265 Additions 63,700 Payments (158,677) Other changes, including accretion 3,762 Balance as of September 30, 2024 $ 117,050 The level 3 valuations of the deferred purchase obligations were determined utilizing Monte-Carlo models and take into account our forecasted projections as they relate to the underlying performance of the respective businesses. The Monte-Carlo simulation model applied in assessing the fair value of the deferred purchase obligation associated with the ITRenew Transaction incorporates assumptions as to expected gross profits over the achievement period, including adjustments for the volatility of timing and amount of the associated revenue and costs, as well as discount rates that account for the risk of the arrangement and overall market risks. The Monte-Carlo simulation model applied in assessing the fair value of the deferred purchase obligation associated with the Regency Transaction incorporates assumptions as to expected revenue over the achievement period, including adjustments for volatility and timing, as well as discount rates that account for the risk of the arrangement and overall market risks. Any material change to these assumptions may result in a significantly higher or lower fair value of the related deferred purchase obligation. There were no material items that were measured at fair value on a non-recurring basis at September 30, 2024 and December 31, 2023 other than (i) those disclosed in Note 2.p. to Notes to Consolidated Financial Statements included in our Annual Report and (ii) assets acquired and liabilities assumed through our acquisitions that occurred during the nine months ended September 30, 2024 (see Note 3), both of which are based on Level 3 inputs. F. ACCUMULATED OTHER COMPREHENSIVE ITEMS, NET The changes in Accumulated other comprehensive items, net for the three and nine months ended September 30, 2024 and 2023 are as follows: THREE MONTHS ENDED SEPTEMBER 30, 2024 THREE MONTHS ENDED SEPTEMBER 30, 2023 FOREIGN DERIVATIVE FINANCIAL TOTAL FOREIGN DERIVATIVE FINANCIAL TOTAL Beginning of Period $ (471,935) $ 10,844 $ (461,091) $ (396,677) $ 14,433 $ (382,244) Other comprehensive income (loss): Foreign currency translation and other adjustments 106,861 — 106,861 (79,416) — (79,416) Change in fair value of derivative instruments — (34,281) (34,281) — 6,184 6,184 Reclassifications from accumulated other comprehensive items, net — — — — (2,527) (2,527) Total other comprehensive income (loss) 106,861 (34,281) 72,580 (79,416) 3,657 (75,759) End of Period $ (365,074) $ (23,437) $ (388,511) $ (476,093) $ 18,090 $ (458,003) NINE MONTHS ENDED SEPTEMBER 30, 2024 NINE MONTHS ENDED SEPTEMBER 30, 2023 FOREIGN DERIVATIVE FINANCIAL TOTAL FOREIGN DERIVATIVE FINANCIAL TOTAL Beginning of Period $ (373,628) $ 2,472 $ (371,156) $ (454,509) $ 12,506 $ (442,003) Other comprehensive income (loss): Foreign currency translation and other adjustments 8,554 — 8,554 (21,584) — (21,584) Change in fair value of derivative instruments — (23,381) (23,381) — 10,638 10,638 Reclassifications from accumulated other comprehensive items, net — (2,528) (2,528) — (5,054) (5,054) Total other comprehensive income (loss) 8,554 (25,909) (17,355) (21,584) 5,584 (16,000) End of Period $ (365,074) $ (23,437) $ (388,511) $ (476,093) $ 18,090 $ (458,003) G. REVENUES The costs associated with the initial movement of customer records into physical storage and certain commissions are considered costs to fulfill or obtain customer contracts (collectively, "Contract Costs"). Contract Costs as of September 30, 2024 and December 31, 2023 are as follows: SEPTEMBER 30, 2024 DECEMBER 31, 2023 GROSS ACCUMULATED NET GROSS ACCUMULATED NET Intake Costs asset $ 84,021 $ (40,865) $ 43,156 $ 76,150 $ (39,617) $ 36,533 Commissions asset 190,432 (72,480) 117,952 156,639 (64,279) 92,360 Deferred revenue liabilities are reflected in our Condensed Consolidated Balance Sheets as follows: DESCRIPTION LOCATION IN BALANCE SHEET SEPTEMBER 30, 2024 DECEMBER 31, 2023 Deferred revenue - Current Deferred revenue $ 294,545 $ 325,665 Deferred revenue - Long-term Other Long-term Liabilities 85,795 100,770 DATA CENTER LESSOR CONSIDERATIONS Our Global Data Center Business features storage rental provided to customers at contractually specified rates over a fixed contractual period, which are accounted for in accordance with Accounting Standards Codification 842, Leases . Storage rental revenue associated with our Global Data Center Business for the three and nine months ended September 30, 2024 and 2023 is as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2024 2023 2024 2023 Storage rental revenue $ 150,796 $ 123,655 $ 438,221 $ 342,080 H. STOCK-BASED COMPENSATION Our stock-based compensation expense includes the cost of stock options, restricted stock units ("RSUs") and performance units ("PUs") (together, the "Employee Stock-Based Awards"). STOCK-BASED COMPENSATION EXPENSE Stock-based compensation expense for the Employee Stock-Based Awards for the three and nine months ended September 30, 2024 and 2023 is as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2024 2023 2024 2023 Stock-based compensation expense $ 29,563 $ 18,313 $ 73,491 $ 53,195 During the nine months ended September 30, 2024, we granted approximately 83,100 stock options, 670,900 RSUs and 453,000 PUs under the 2014 Plan (as defined in Note 2.t to Notes to Consolidated Financial Statements included in our Annual Report). As of September 30, 2024, unrecognized compensation cost related to the unvested po I. ACQUISITION AND INTEGRATION COSTS Acquisition and integration costs represent operating expenditures directly associated with the closing and integration activities of our business acquisitions that have closed, or are highly probable of closing, and include (i) advisory, legal and professional fees to complete business acquisitions and (ii) costs to integrate acquired businesses into our existing operations, including move, severance and system integration costs (collectively, "Acquisition and Integration Costs"). Acquisition and Integration Costs for the three and nine months ended September 30, 2024 and 2023 are as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2024 2023 2024 2023 Acquisition and Integration Costs $ 11,262 $ 9,909 $ 28,573 $ 13,015 J. LOSS (GAIN) ON DISPOSAL/WRITE-DOWN OF PROPERTY, PLANT AND EQUIPMENT, NET Loss (gain) on disposal/write-down of property, plant and equipment, net for the three and nine months ended September 30, 2024 and 2023 is as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2024 2023 2024 2023 (1) Loss (gain) on disposal/write-down of property, plant and equipment, net $ 5,091 $ (4,416) $ 8,270 $ (18,982) (1) The gains for the nine months ended September 30, 2023 primarily consist of a gain of approximately $18,500 associated with a sale-leaseback transaction of a facility in Singapore during the first quarter 2023. The gains recognized during 2023 are the result of our program to monetize a small portion of our industrial assets through sale and sale-leaseback transactions. The terms for these leases are consistent with the terms of our lease portfolio, which are disclosed in detail in Note 2.j. to Notes to Consolidated Financial Statements included in our Annual Report. K. OTHER EXPENSE (INCOME), NET Other expense (income), net for the three and nine months ended September 30, 2024 and 2023 consists of the following: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, DESCRIPTION 2024 2023 2024 2023 Foreign currency transaction losses (gains), net (1)(2) $ 46,657 $ (29,310) $ 31,291 $ 177 Debt extinguishment expense 5,417 — 5,417 — Other, net (3)(4) 34,288 13,039 42,957 67,702 Other Expense (Income), Net $ 86,362 $ (16,271) $ 79,665 $ 67,879 (1) The losses for the three and nine months ended September 30, 2024 primarily consist of the impact of changes in the exchange rate of the British pound sterling and the Euro against the United States dollar on our intercompany balances with and between certain of our subsidiaries. (2) The gains for the three months ended September 30, 2023 primarily consist of the impact of changes in the exchange rate of the British pound sterling against the United States dollar on our intercompany balances with and between certain of our subsidiaries. (3) Other, net for the three and nine months ended September 30, 2024 primarily consists of approximately $29,200 in charges associated with the agreement to purchase the remaining interest in the Web Werks JV (as defined and discussed in Note 3) as well as losses on our equity method investments and the change in value of our deferred purchase obligations. (4) Other, net for the nine months ended September 30, 2023 primarily consists of a loss of approximately $38,000 associated with the remeasurement to fair value of our previously held equity interest in the Clutter JV (as defined and discussed in Note 10) as well as losses on our equity method investments and the change in value of our deferred purchase obligations. L. INCOME TAXES We provide for income taxes during interim periods based on our estimate of the effective tax rate for the year. Our effective tax rates for the three and nine months ended September 30, 2024 and 2023 are as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2024 (1) 2023 (2) 2024 (1) 2023 (2) Effective Tax Rate 58.3 % 9.8 % 35.2 % 16.4 % (1) The primary reconciling items between the federal statutory tax rate of 21.0% and our overall effective tax rate for the three and nine months ended September 30, 2024 were the lack of tax benefits recognized for the year to date ordinary losses of certain entities, the benefits derived from the dividends paid deduction and the differences in the tax rates to which our foreign earnings are subject. In addition, we recorded gains and losses in Other expense (income), net during the period, for which there was no tax impact. (2) The primary reconciling items between the federal statutory tax rate of 21.0% and our overall effective tax rate for the three and nine months ended September 30, 2023 were the benefits derived from the dividends paid deduction and the differences in the tax rates to which our foreign earnings are subject. In addition, we recorded gains and losses in Other expense (income), net during the period, for which there was no tax impact. M. INCOME (LOSS) PER SHARE—BASIC AND DILUTED The calculations of basic and diluted income (loss) per share for the three and nine months ended September 30, 2024 and 2023 are as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2024 2023 2024 2023 Net (Loss) Income $ (33,665) $ 91,391 $ 77,981 $ 158,069 Less: Net (Loss) Income Attributable to Noncontrolling Interests (45) 348 1,757 2,317 Net (Loss) Income Attributable to Iron Mountain Incorporated (utilized in numerator of Earnings Per Share calculation) $ (33,620) $ 91,043 $ 76,224 $ 155,752 Weighted-average shares—basic 293,603,000 292,148,000 293,229,000 291,805,000 Effect of dilutive potential stock options — 1,592,000 2,143,000 1,376,000 Effect of dilutive potential RSUs and PUs — 529,000 540,000 434,000 Weighted-average shares—diluted 293,603,000 294,269,000 295,912,000 293,615,000 Net (Loss) Income Per Share Attributable to Iron Mountain Incorporated: Basic $ (0.11) $ 0.31 $ 0.26 $ 0.53 Diluted $ (0.11) $ 0.31 $ 0.26 $ 0.53 Antidilutive stock options, RSUs and PUs excluded from the calculation 3,083,222 16,820 293,457 106,561

Acquisitions

Acquisitions	9 Months Ended
	Sep. 30, 2024
Business Combination, Asset Acquisition, and Joint Venture Formation [Abstract]
Acquisitions	ACQUISITIONS WISETEK On September 20, 2024, in order to further expand our asset lifecycle management ("ALM") business, we acquired 100% of Wisetek Solutions Limited ("Wisetek"), an information technology ("IT") asset disposition services provider offering services across the globe with operations facilities in the United States, Ireland, the United Kingdom and Thailand, for (i) cash consideration of approximately 46,600 Euros (or approximately $51,900, based upon the exchange rate between the Euro and the United States dollar on the closing date of this acquisition), subject to adjustments, and (ii) up to 4,200 Euros (or approximately $4,700, based upon the exchange rate between the Euro and the United States dollar as of September 30, 2024) of additional consideration, payable based on the achievement of certain gross profit targets through September 2026. REGENCY TECHNOLOGIES On January 3, 2024, in order to expand our ALM business, we acquired 100% of RSR Partners, LLC (doing business as Regency Technologies), an IT asset disposition services provider with operations throughout the United States, for an initial purchase price of approximately $200,000, subject to certain working capital adjustments at, and subsequent to, the closing, with $125,000 paid at closing, funded by borrowings under the Revolving Credit Facility (as defined in Note 6), and the remaining $75,000 (the “January 2025 Payment”) to be paid in January 2025 (the "Regency Transaction"). The present value of the January 2025 Payment is included as a component of Accrued expenses and other current liabilities in our Condensed Consolidated Balance Sheet at September 30, 2024. The agreement for the Regency Transaction also includes a performance-based contingent consideration with a potential earnout range from zero to $200,000 based upon achievement of certain three-year cumulative revenue targets, which would be payable in 2027, if earned (the “Regency Deferred Purchase Obligation”). The preliminary fair value estimate of the Regency Deferred Purchase Obligation as of the acquisition date was approximately $78,400. See Note 2.e. for details on the methodology used to establish the fair value. The fair value of the Regency Deferred Purchase Obligation is included as a component of Other long-term liabilities in our Condensed Consolidated Balance Sheet at September 30, 2024. Subsequent increases or decreases in the fair value estimate of the Regency Deferred Purchase Obligation, as well as the accretion of the discount to present value, is included as a component of Other expense (income), net in our Condensed Consolidated Statements of Operations until the deferred purchase obligation is settled or paid. Subsequent to the acquisition, the results of Regency Technologies are included as a component of Corporate and Other. PRELIMINARY PURCHASE PRICE ALLOCATION A summary of the cumulative consideration paid and the preliminary allocation of the purchase price paid for our acquisitions closed during the nine months ended September 30, 2024 is as follows: NINE MONTHS ENDED SEPTEMBER 30, 2024 Cash Paid (gross of cash acquired) $ 184,777 Deferred Purchase Obligations, Purchase Price Holdbacks and Other (1) 133,813 Total Consideration 318,590 Fair Value of Identifiable Assets Acquired (2) 212,826 Fair Value of Identifiable Liabilities Acquired (62,525) Goodwill Initially Recorded (3) $ 168,289 (1) Consists of the acquisition-date fair values of the Regency Deferred Purchase Obligation and the January 2025 Payment. (2) Assets acquired include supplier relationship intangible assets, with a total fair value of approximately $131,000 and a weighted average life of approximately 18 years. (3) Goodwill is primarily attributable to the assembled workforce, expanded market opportunities and costs and other operating synergies anticipated upon the integration of the operations of us and the acquired businesses. The preliminary purchase price allocations that are not finalized as of September 30, 2024 relate to the final assessment of the fair values of the assets acquired and the fair value of the deferred purchase obligation, which may differ materially from these preliminary estimates associated with the acquisitions closed during the nine months ended September 30, 2024. Any adjustments to our estimates of purchase price allocations will be made in the periods in which the adjustments are determined, and the cumulative effect of such adjustments will be calculated as if the adjustments had been completed as of the acquisition dates. Purchase price allocation adjustments recorded during the nine months ended September 30, 2024 were not material to our balance sheet or results from operations. PRIOR YEAR ACQUISITION UPDATE On July 1, 2024, we entered into an agreement with the minority shareholders of Web Werks India Private Limited to acquire the remaining approximately 36.61% interest in the Web Werks JV (as defined in Note 5 to Notes to Consolidated Financial Statements included in our Annual Report) in two separate transactions. As a result of the agreement, during the three months ended September 30, 2024, we recognized a charge of approximately $29,200, which is included as a component of Other expense (income), net in our Condensed Consolidated Statements of Operations. On July 5, 2024, we completed the acquisition of an approximately 8.55% interest in the Web Werks JV (“Tranche I”) for approximately 3,000,000 Indian rupees (or approximately $35,000, based upon the exchange rate between the United States dollar and the Indian rupee on the closing date of Tranche I). Subsequent to the Tranche I payment, our ownership interest in the Web Werks JV is approximately 71.94%. In March 2025, we will be required to make an additional payment of approximately 9,600,000 Indian rupees (or approximately $114,600, based upon the exchange rate between the United States dollar and the Indian rupee as of September 30, 2024) to acquire the remaining approximately 28.06% interest in the Web Werks JV ("Tranche II"). As part of the Tranche II payment in March 2025, we may also make an incremental payment of approximately 1,000,000 Indian rupees (or approximately $11,900, based upon the exchange rate between the United States dollar and the Indian rupee as of September 30, 2024) (the "Incremental Payment") if certain infrastructure goals are achieved before December 31, 2024. The liability associated with Tranche II and our current estimate of the Incremental Payment is included within Accrued expenses and other current liabilities in our Condensed Consolidated Balance Sheet at September 30, 2024.

Investments

Investments	9 Months Ended
	Sep. 30, 2024
Investments, All Other Investments [Abstract]
Investments	INVESTMENTS JOINT VENTURE SUMMARY Our joint venture with AGC Equity Partners (the "Frankfurt JV") is accounted for as an equity method investment and is presented as a component of Other within Other assets, net in our Condensed Consolidated Balance Sheets. The carrying value and equity interest in the Frankfurt JV at September 30, 2024 and December 31, 2023 is as follows: SEPTEMBER 30, 2024 DECEMBER 31, 2023 CARRYING VALUE EQUITY INTEREST CARRYING VALUE EQUITY INTEREST Frankfurt JV $ 65,219 20 % $ 57,874 20 %

Derivative Instruments and Hedg

Derivative Instruments and Hedging Activities	9 Months Ended
	Sep. 30, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities	DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES Derivative instruments we are party to include: (i) interest rate swap agreements (which are designated as cash flow hedges) and (ii) cross-currency swap agreements (which are designated as net investment hedges). INTEREST RATE SWAP AGREEMENTS DESIGNATED AS CASH FLOW HEDGES We utilize interest rate swap agreements designated as cash flow hedges to limit our exposure to changes in interest rates on a portion of our floating rate indebtedness. Certain of our interest rate swap agreements have notional amounts that will increase with the underlying hedged transaction. Under our interest rate swap agreements, we receive variable rate interest payments associated with the notional amount of each interest rate swap, based upon the one-month Secured Overnight Financing Rate ("SOFR"), in exchange for the payment of fixed interest rates as specified in the interest rate swap agreements. Our interest rate swap agreements are marked to market at the end of each reporting period, representing the fair values of the interest rate swap agreements, and any changes in fair value are recognized as a component of Accumulated other comprehensive items, net. Unrealized gains are recognized as assets, while unrealized losses are recognized as liabilities. As of September 30, 2024 and December 31, 2023, we have approximately $1,354,000 and $520,000, respectively, in notional value outstanding on our interest rate swap agreements. As of September 30, 2024, our interest rate swap agreements have maturity dates ranging from October 2025 through May 2027. CROSS-CURRENCY SWAP AGREEMENTS DESIGNATED AS A HEDGE OF NET INVESTMENT We utilize cross-currency swaps to hedge the variability of exchange rate impacts between the United States dollar and the Euro. As of both September 30, 2024 and December 31, 2023, we have approximately $509,200 in notional value outstanding on cross-currency interest rate swaps. As of September 30, 2024, our cross-currency interest rate swaps have maturity dates ranging from August 2025 through February 2026. We have designated these cross-currency swap agreements as hedges of net investments in certain of our Euro denominated subsidiaries and they require an exchange of the notional amounts at maturity. These cross-currency swap agreements are marked to market at the end of each reporting period, representing the fair values of the cross-currency swap agreements, and any changes in fair value are recognized as a component of Accumulated other comprehensive items, net. Unrealized gains are recognized as assets while unrealized losses are recognized as liabilities. The excluded component of our cross-currency swap agreements is recorded in Accumulated other comprehensive items, net and amortized to interest expense on a straight-line basis. The fair values of derivative instruments recognized in our Condensed Consolidated Balance Sheets at September 30, 2024 and December 31, 2023, by derivative instrument, are as follows: SEPTEMBER 30, 2024 DECEMBER 31, 2023 DERIVATIVE INSTRUMENTS (1) Assets Liabilities Assets Liabilities Cash Flow Hedges (2) Interest rate swap agreements $ — $ (25,053) $ 1,601 $ (3,273) Net Investment Hedges (3) Cross-currency swap agreements — (4,771) 4,758 (2,496) (1) Our derivative assets are included as a component of (i) Prepaid expenses and other or (ii) Other within Other assets, net and our derivative liabilities are included as a component of (i) Accrued expenses and other current liabilities or (ii) Other long-term liabilities in our Condensed Consolidated Balance Sheets. As of September 30, 2024, $1,848 is included within Accrued expenses and other current liabilities and $27,976 is included within Other long-term liabilities. As of December 31, 2023, $6,359 is included within Other assets, $2,496 is included within Accrued expenses and other current liabilities and $3,273 is included within Other long-term liabilities. (2) As of September 30, 2024, cumulative net losses recorded within Accumulated other comprehensive items, net associated with our interest rate swap agreements are $23,437. (3) As of September 30, 2024, cumulative net gains recorded within Accumulated other comprehensive items, net associated with our cross-currency swap agreements are $37,955, which include $42,726 related to the excluded component of our cross-currency swap agreements. Unrealized (losses) gains recognized in Accumulated other comprehensive items, net during the three and nine months ended September 30, 2024 and 2023, by derivative instrument, are as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, DERIVATIVE INSTRUMENTS 2024 2023 2024 2023 Cash Flow Hedges Interest rate swap agreements $ (34,281) $ 6,184 $ (23,381) $ 10,638 Net Investment Hedges Cross-currency swap agreements (18,480) 5,822 (7,033) (15,685) Cross-currency swap agreements (excluded component) 4,176 5,270 12,529 16,921 (Losses) gains recognized in Net income (loss) during the three and nine months ended September 30, 2024 and 2023, by derivative instrument, are as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, DERIVATIVE INSTRUMENTS Location of (loss) gain 2024 2023 2024 2023 Cash Flow Hedges Interest rate swap agreements Interest expense $ — $ 2,527 $ 2,528 $ 5,054 Net Investment Hedges Cross-currency swap agreements (excluded component) Interest expense (4,176) (5,270) (12,529) (16,921)

Debt

Debt	9 Months Ended
	Sep. 30, 2024
Debt Disclosure [Abstract]
Debt	DEBT Long-term debt is as follows: SEPTEMBER 30, 2024 DECEMBER 31, 2023 DEBT (INCLUSIVE OF DISCOUNT) UNAMORTIZED DEFERRED FINANCING COSTS CARRYING AMOUNT FAIR VALUE DEBT (INCLUSIVE OF DISCOUNT) UNAMORTIZED DEFERRED FINANCING COSTS CARRYING AMOUNT FAIR VALUE Revolving Credit Facility (1) $ 1,005,000 $ (3,763) $ 1,001,237 $ 1,005,000 $ — $ (4,621) $ (4,621) $ — Term Loan A (1) 218,750 — 218,750 218,750 228,125 — 228,125 228,125 Term Loan B due 2026 (1) — — — — 659,298 (2,498) 656,800 659,750 Term Loan B due 2031 (1) 1,849,096 (15,462) 1,833,634 1,860,045 1,191,000 (13,026) 1,177,974 1,200,000 Virginia 3 Term Loans (2) 246,188 (3,336) 242,852 246,188 101,218 (4,641) 96,577 101,218 Virginia 4/5 Term Loans (2) 70,280 (3,483) 66,797 70,280 16,338 (5,892) 10,446 16,338 Virginia 6 Term Loans (3) 95,062 (5,106) 89,956 95,062 — — — — Australian Dollar Term Loan (2) 197,427 (336) 197,091 198,501 197,743 (482) 197,261 199,195 UK Bilateral Revolving Credit Facility (2) 187,431 (1,168) 186,263 187,431 178,239 — 178,239 178,239 GBP Notes (2) 535,518 (1,095) 534,423 527,239 509,254 (1,763) 507,491 489,108 4 7 / 8 % Notes due 2027 (2) 1,000,000 (4,266) 995,734 987,500 1,000,000 (5,332) 994,668 967,500 5 1 / 4 % Notes due 2028 (2) 825,000 (4,133) 820,867 818,813 825,000 (5,019) 819,981 800,250 5% Notes due 2028 (2) 500,000 (2,773) 497,227 491,250 500,000 (3,316) 496,684 478,750 7% Notes due 2029 (2) 1,000,000 (9,218) 990,782 1,037,500 1,000,000 (10,813) 989,187 1,027,500 4 7 / 8 % Notes due 2029 (2) 1,000,000 (7,233) 992,767 975,000 1,000,000 (8,318) 991,682 945,000 5 1 / 4 % Notes due 2030 (2) 1,300,000 (8,775) 1,291,225 1,280,500 1,300,000 (9,903) 1,290,097 1,241,500 4 1 / 2 % Notes (2) 1,100,000 (7,985) 1,092,015 1,039,500 1,100,000 (8,917) 1,091,083 995,500 5% Notes due 2032 (2) 750,000 (10,227) 739,773 721,875 750,000 (11,206) 738,794 684,375 5 5 / 8 % Notes (2) 600,000 (4,549) 595,451 595,500 600,000 (4,985) 595,015 567,000 Real Estate Mortgages, Financing Lease Liabilities and Other 611,321 (1,922) 609,399 611,321 519,907 (403) 519,504 519,907 Accounts Receivable Securitization Program 386,500 (734) 385,766 386,500 358,500 (317) 358,183 358,183 Total Long-term Debt 13,477,573 (95,564) 13,382,009 12,034,622 (101,452) 11,933,170 Less Current Portion (136,547) — (136,547) (120,670) — (120,670) Long-term Debt, Net of Current Portion $ 13,341,026 $ (95,564) $ 13,245,462 $ 11,913,952 $ (101,452) $ 11,812,500 (1) Collectively, the “Credit Agreement”. The Credit Agreement consists of a revolving credit facility (the “Revolving Credit Facility”), a term loan A facility (the “Term Loan A”) and a term loan B facility (the "Term Loan B due 2031"). The Credit Agreement also included a second term loan B facility (the "Term Loan B due 2026") until its extinguishment in August 2024. The remaining amount available for borrowing under the Revolving Credit Facility as of September 30, 2024 was $1,237,020 (which represents the maximum availability as of such date). The weighted average interest rate in effect under the Revolving Credit Facility was 7.0% as of September 30, 2024. Due to the discontinuance of the Canadian Dollar Offered Rate reference rate on June 28, 2024, the Credit Agreement was amended on June 7, 2024 to update the interest rate benchmark available for Canadian currency borrowings under our Revolving Credit Facility to the Canadian Overnight Repo Rate Average, effective July 1, 2024. All other material terms of the Revolving Credit Facility remain the same as disclosed in Note 7 to Notes to Consolidated Financial Statements included in our Annual Report. (2) Each as defined in Note 7 to Notes to Consolidated Financial Statements included in our Annual Report. (3) The fair value (Level 2 of the fair value hierarchy described at Note 2.e.) of this debt instrument approximates the carrying value as borrowings under this debt instrument are based on a current variable market interest rate. See Note 7 to Notes to Consolidated Financial Statements included in our Annual Report for additional information regarding our long-term debt, including the direct obligors of each of our debt instruments as well as information regarding the fair value of our debt instruments (including the levels of the fair value hierarchy used to determine the fair value of our debt instruments, which are consistent with the levels of the fair value hierarchy used to determine the fair value of our debt as of September 30, 2024). CREDIT AGREEMENT On July 2, 2024, we amended the Credit Agreement, which resulted in (i) an increase in the principal amount of the Term Loan B due 2031 from approximately $1,194,000 to approximately $1,806,700, (ii) a decrease in the interest rate of the Term Loan B due 2031 from SOFR plus 2.25% to SOFR plus 2.00% and (iii) a decrease in the principal amount of our Term Loan B due 2026 from approximately $656,300 to approximately $53,400. We paid original issue discount fees of approximately $4,300 in connection with this amendment. On August 19, 2024, we repaid the remaining approximately $53,400 principal balance of the Term Loan B due 2026 and amended the Credit Agreement to increase the principal amount of the Term Loan B due 2031 from approximately $1,806,700 to approximately $1,860,000. As a result of these amendments, we recorded a charge to Other expense (income), net related to the extinguishment of debt. Quarterly principal payments of approximately $4,700 on the Term Loan B due 2031 commenced in September 2024. All other material terms remain the same as disclosed in Note 7 to Notes to Consolidated Financial Statements included in our Annual Report. VIRGINIA CREDIT AGREEMENTS As our Global Data Center business continues to expand, we have entered into credit agreements in order to partially finance the construction of various data centers. During the second quarter of 2024, we entered into two new agreements. These agreements primarily consist of the following term loan facilities: AGREEMENT MAXIMUM BORROWING OUTSTANDING BORROWINGS AS OF SEPTEMBER 30, 2024 DIRECT CONTRACTUAL INTEREST RATE UNUSED COMMITMENT FEE MATURITY DATE (1) Virginia 6 Term Loans (2) $ 210,000 $ 95,062 Iron Mountain Data Centers Virginia 6, LLC SOFR plus 2.75% 0.75% May 3, 2027 Virginia 7 Term Loans (3) 300,000 — Iron Mountain Data Centers Virginia 7, LLC SOFR plus 2.50% 0.75% April 12, 2027 (1) All obligations will become due on the specified maturity dates. Each agreement includes two one-year options that allow us to extend the initial maturity date, subject to the conditions specified in the agreements. (2) On May 3, 2024, Iron Mountain Data Centers Virginia 6, LLC, a wholly-owned subsidiary of Iron Mountain Data Centers Virginia 6/7 JV, LLC, entered into a credit agreement (the "Virginia 6 Credit Agreement"). The Virginia 6 Credit Agreement consists of a term loan facility (the "Virginia 6 Term Loans") and a letter of credit facility. The Virginia 6 Credit Agreement is secured by the equity interests and assets of Iron Mountain Data Centers Virginia 6, LLC. As of September 30, 2024, the interest rate in effect under the Virginia 6 Credit Agreement was 4.9%. (3) On April 12, 2024, Iron Mountain Data Centers Virginia 7, LLC, a wholly-owned subsidiary of Iron Mountain Data Centers Virginia 6/7 JV, LLC, entered into a credit agreement (the "Virginia 7 Credit Agreement"). The Virginia 7 Credit Agreement consists of a term loan facility and a letter of credit facility. The Virginia 7 Credit Agreement is secured by the equity interests and assets of Iron Mountain Data Centers Virginia 7, LLC. UK BILATERAL REVOLVING CREDIT FACILITY MAXIMUM AMOUNT £140,000 OPTIONAL ADDITIONAL COMMITMENTS £125,000 INTEREST RATE 7.0% As of September 30, 2024 Iron Mountain (UK) PLC and Iron Mountain (UK) Data Centre Limited (collectively, the "UK Borrowers") have a British pounds sterling Revolving Credit Facility (the "UK Bilateral Revolving Credit Facility") with Barclays Bank PLC. The maximum amount permitted to be borrowed under the UK Bilateral Revolving Credit Facility is 140,000 British pounds sterling, which was fully drawn as of September 30, 2024. We have the option to request additional commitments of up to 125,000 British pounds sterling, subject to conditions specified in the UK Bilateral Revolving Credit Facility. On September 10, 2024, the UK Borrowers amended the UK Bilateral Revolving Credit Facility to extend the maturity date from September 24, 2025 to September 24, 2026. All other material terms of the UK Bilateral Revolving Credit Facility remain consistent with what was disclosed in Note 7 to Notes to Consolidated Financial Statements included in our Annual Report. ACCOUNTS RECEIVABLE SECURITIZATION PROGRAM On June 14, 2024, we amended the Accounts Receivable Securitization Program (as defined in Note 7 to Notes to Consolidated Financial Statements included in our Annual Report) to (i) increase the maximum borrowing capacity from $360,000 to $400,000, with an option to increase the borrowing capacity to $450,000, and (ii) extend the maturity date from July 1, 2025 to July 1, 2027, at which point all obligations become due. All other material terms of the Accounts Receivable Securitization Program remain the same as disclosed in Note 7 to Notes to Consolidated Financial Statements included in our Annual Report. MAXIMUM AMOUNT $400,000 OUTSTANDING BORROWING $386,500 INTEREST RATE 5.9% As of September 30, 2024 LETTERS OF CREDIT As of September 30, 2024, we have outstanding letters of credit totaling $79,530, of which $7,980 reduce our borrowing capacity under the Revolving Credit Facility. The letters of credit expire at various dates between October 2024 and July 2025. DEBT COVENANTS The Credit Agreement, our bond indentures and other agreements governing our indebtedness contain certain restrictive financial and operating covenants, including covenants that restrict our ability to complete acquisitions, pay cash dividends, incur indebtedness, make investments, sell assets and take other specified corporate actions. The covenants do not contain a rating trigger. Therefore, a change in our debt rating would not trigger a default under the Credit Agreement, our bond indentures or other agreements governing our indebtedness. The Credit Agreement requires that we satisfy a net total lease adjusted leverage ratio and a fixed charge coverage ratio on a quarterly basis, and our bond indentures require that, among other things, we satisfy a leverage ratio (not lease adjusted) or a fixed charge coverage ratio (not lease adjusted) as a condition to taking actions such as paying dividends and incurring indebtedness. The Credit Agreement uses earnings before interest, taxes, depreciation and amortization and rent expense ("EBITDAR") based calculations and the bond indentures use earnings before interest, taxes, depreciation and amortization ("EBITDA") based calculations as the primary measures of financial performance for purposes of calculating leverage and fixed charge coverage ratios. The EBITDAR- and EBITDA-based leverage calculations include our consolidated subsidiaries, other than those we have designated as "Unrestricted Subsidiaries" as defined in the Credit Agreement and bond indentures. Generally, the Credit Agreement and the bond indentures use a trailing four fiscal quarter basis for purposes of the relevant calculations and require certain adjustments and exclusions for purposes of those calculations, which make the calculation of financial performance for purposes of those calculations under the Credit Agreement and bond indentures not directly comparable to Adjusted EBITDA as presented herein. We are in compliance with our leverage and fixed charge coverage ratios under the Credit Agreement, our bond indentures and other agreements governing our indebtedness as of September 30, 2024. Noncompliance with these leverage and fixed charge coverage ratios would have a material adverse effect on our financial condition and liquidity.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES We are involved in litigation from time to time in the ordinary course of business, including litigation arising from damage to customer assets in our facilities caused by fires and other natural disasters. While the outcome of litigation is inherently uncertain, we do not believe any current litigation will have a material adverse effect on our consolidated financial condition, results of operations or cash flows. We have estimated a reasonably possible range for all loss contingencies and believe it is reasonably possible that we could incur aggregate losses in addition to amounts currently accrued for all matters up to an additional $14,000 over the next several years, of which certain amounts would be covered by insurance or indemnity arrangement.

Stockholders' Equity Matters

Stockholders' Equity Matters	9 Months Ended
	Sep. 30, 2024
Equity [Abstract]
Stockholders' Equity Matters	STOCKHOLDERS' EQUITY MATTERS DIVIDENDS In fiscal year 2023 and the nine months ended September 30, 2024, our board of directors declared the following dividends: DECLARATION DATE DIVIDEND RECORD DATE TOTAL PAYMENT DATE February 23, 2023 $ 0.6185 March 15, 2023 $ 180,339 April 5, 2023 May 4, 2023 0.6185 June 15, 2023 180,493 July 6, 2023 August 3, 2023 0.6500 September 15, 2023 189,730 October 5, 2023 November 2, 2023 0.6500 December 15, 2023 189,886 January 4, 2024 February 22, 2024 0.6500 March 15, 2024 190,506 April 4, 2024 May 2, 2024 0.6500 June 17, 2024 190,643 July 5, 2024 August 1, 2024 0.7150 September 16, 2024 209,776 October 3, 2024 On November 6, 2024, we declared a dividend to our stockholders of record as of December 16, 2024 of $0.715 per share, payable on January 7, 2025. NONCONTROLLING INTERESTS Our data center operations include two joint ventures which are consolidated within our Global Data Center Business segment as we have concluded we have control over the joint ventures. During the quarter ended September 30, 2024, a put option available to our partner in our Iron Mountain Data Centers Virginia 4/5 JV, LP joint venture expired, triggering a change in the presentation of the related noncontrolling interest. The noncontrolling interest of approximately $53,400 was previously presented as Redeemable noncontrolling interests in our Consolidated Balance Sheets and is now presented as Noncontrolling interests within stockholders’ equity in our Condensed Consolidated Balance Sheet at September 30, 2024. During the quarter ended September 30, 2024, we entered into an agreement with a partner to form our Iron Mountain Data Centers Virginia 6/7 JV, LLC joint venture, which resulted in Noncontrolling interests of approximately $103,100 in our Condensed Consolidated Balance Sheet at September 30, 2024.

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2024
Segment Reporting [Abstract]
Segment Information	SEGMENT INFORMATION Our reportable segments as of December 31, 2023 are described in Note 11 to Notes to Consolidated Financial Statements included in our Annual Report and are as follows: • Global RIM Business • Global Data Center Business The remaining activities of our business consist primarily of our Fine Arts and ALM businesses and other corporate items ("Corporate and Other"). The operations associated with acquisitions completed during the first nine months of 2024 have been incorporated into Corporate and Other. An analysis of our business segment information and reconciliation to the accompanying Condensed Consolidated Financial Statements for the three and nine months ended September 30, 2024 and 2023 is as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2024 2023 2024 2023 Global RIM Business Total Revenues $ 1,260,358 $ 1,182,652 $ 3,721,092 $ 3,469,045 Adjusted EBITDA 568,994 516,548 1,644,004 1,493,394 Global Data Center Business Total Revenues $ 153,206 $ 127,535 $ 449,845 $ 357,873 Adjusted EBITDA 66,796 53,216 194,381 157,660 Corporate and Other Total Revenues $ 143,794 $ 77,988 $ 397,693 $ 233,542 Adjusted EBITDA (67,677) (69,802) (207,056) (214,626) Total Consolidated Total Revenues $ 1,557,358 $ 1,388,175 $ 4,568,630 $ 4,060,460 Adjusted EBITDA 568,113 499,962 1,631,329 1,436,428 Adjusted EBITDA for each segment is defined as net income (loss) before interest expense, net, provision (benefit) for income taxes, depreciation and amortization (inclusive of our share of Adjusted EBITDA from our unconsolidated joint ventures), and excluding certain items we do not believe to be indicative of our core operating results, specifically: EXCLUDED • Acquisition and Integration Costs • Restructuring and other transformation • Loss (gain) on disposal/write-down of property, plant and equipment, net (including real estate) • Other expense (income), net • Stock-based compensation expense • Intangible impairments Internally, we use Adjusted EBITDA as the basis for evaluating the performance of, and allocating resources to, our operating segments. A reconciliation of Net (Loss) Income to Adjusted EBITDA on a consolidated basis for the three and nine months ended September 30, 2024 and 2023 is as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2024 2023 2024 2023 Net (Loss) Income $ (33,665) $ 91,391 $ 77,981 $ 158,069 Add/(Deduct): Interest expense, net 186,067 152,801 527,107 434,148 Provision (benefit) for income taxes 12,400 9,912 42,328 30,925 Depreciation and amortization 232,240 198,757 666,296 576,218 Acquisition and Integration Costs 11,262 9,909 28,573 13,015 Restructuring and other transformation 37,282 38,861 124,562 121,362 Loss (gain) on disposal/write-down of property, plant and equipment, net (including real estate) 5,091 (4,416) 8,270 (18,982) Other expense (income), net, excluding our share of losses (gains) from our unconsolidated joint ventures 85,532 (17,626) 76,954 58,559 Stock-based compensation expense 29,563 18,313 73,491 53,195 Our share of Adjusted EBITDA reconciling items from our unconsolidated joint ventures 2,341 2,060 5,767 9,919 Adjusted EBITDA $ 568,113 $ 499,962 $ 1,631,329 $ 1,436,428 Segment revenue by product and service lines for the three and nine months ended September 30, 2024 and 2023 is as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2024 2023 2024 2023 Global RIM Business Records Management (1) $ 990,333 $ 926,424 $ 2,901,465 $ 2,693,046 Data Management (1) 127,583 128,191 390,706 388,036 Information Destruction (1)(2) 142,442 128,037 428,921 387,963 Data Center (1) — — — — Global Data Center Business Records Management (1) $ — $ — $ — $ — Data Management (1) — — — — Information Destruction (1) — — — — Data Center (1) 153,206 127,535 449,845 357,873 Corporate and Other Records Management (1) $ 41,460 $ 36,092 $ 121,528 $ 107,849 Data Management (1) — — — — Information Destruction (1)(3) 102,334 41,896 276,165 125,693 Data Center (1) — — — — Total Consolidated Records Management (1) $ 1,031,793 $ 962,516 $ 3,022,993 $ 2,800,895 Data Management (1) 127,583 128,191 390,706 388,036 Information Destruction (1)(2)(3) 244,776 169,933 705,086 513,656 Data Center (1) 153,206 127,535 449,845 357,873 (1) Each of these offerings has a component of revenue that is storage rental related and a component that is service related, except for information destruction, which does not have a storage rental component. (2) Information destruction revenue for our Global RIM Business includes secure shredding services. (3) Information destruction revenue for Corporate and Other includes product revenue from our ALM business.

Related Parties

Related Parties	9 Months Ended
	Sep. 30, 2024
Related Party Transactions [Abstract]
Related Parties	RELATED PARTIES In October 2020, in connection with the formation of the Frankfurt JV, we entered into agreements whereby we earn various fees, including (i) special project revenue and (ii) property management and construction and development fees for services we are providing to the Frankfurt JV (the "Frankfurt JV Agreements"). In February 2022, we entered into a storage and service agreement with the joint venture formed by Clutter, Inc. and us (the "Clutter JV") to provide certain storage and related services to the Clutter JV (the "Clutter Agreement"). On June 29, 2023, we completed the Clutter Acquisition (as defined in Note 3 to Notes to Consolidated Financial Statements included in our Annual Report) and terminated the Clutter Agreement. Revenue recognized in the accompanying Condensed Consolidated Statements of Operations under these agreements for the three and nine months ended September 30, 2024 and 2023 is as follows (approximately): THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2024 2023 2024 2023 Frankfurt JV Agreements (1) $ 200 $ — $ 2,700 $ 1,700 Clutter Agreement (2) — — — 13,000 (1) Revenue associated with the Frankfurt JV Agreements is presented as a component of our Global Data Center Business segment. (2) Revenue associated with the Clutter Agreement is presented as a component of our Global RIM Business segment.

Restructuring And Other Transfo

Restructuring And Other Transformation	9 Months Ended
	Sep. 30, 2024
Restructuring and Related Activities [Abstract]
Restructuring And Other Transformation	RESTRUCTURING AND OTHER TRANSFORMATION PROJECT MATTERHORN In September 2022, we announced Project Matterhorn. Project Matterhorn investments focus on transforming our operating model to a global operating model. Project Matterhorn focuses on the formation of a solution-based sales approach that is designed to allow us to optimize our shared services and best practices to better serve our customers' needs. We are investing to accelerate growth and to capture a greater share of the large, global addressable markets in which we operate. We expect to incur approximately $150,000 in costs annually related to Project Matterhorn from 2023 through 2025. Costs are comprised of (1) restructuring costs, which include (i) site consolidation and other related exit costs, (ii) employee severance costs and (iii) certain professional fees associated with these activities, and (2) other transformation costs, which include professional fees such as project management costs and costs for third party consultants who are assisting in the enablement of our growth initiatives. Restructuring and other transformation related to Project Matterhorn included in the accompanying Condensed Consolidated Statement of Operations for the three and nine months ended September 30, 2024 and 2023, and from the inception of Project Matterhorn through September 30, 2024, is as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, FROM THE INCEPTION OF PROJECT MATTERHORN THROUGH SEPTEMBER 30, 2024 2024 2023 2024 2023 Restructuring $ 11,556 $ 11,744 $ 38,618 $ 39,828 $ 109,229 Other transformation 25,726 27,117 85,944 81,534 232,481 Restructuring and other transformation $ 37,282 $ 38,861 $ 124,562 $ 121,362 $ 341,710 Restructuring costs for Project Matterhorn, included as a component of Restructuring and other transformation in the accompanying Condensed Consolidated Statement of Operations, by segment, for the three and nine months ended September 30, 2024 and 2023, and from the inception of Project Matterhorn through September 30, 2024, is as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, FROM THE INCEPTION OF PROJECT MATTERHORN THROUGH SEPTEMBER 30, 2024 2024 2023 2024 2023 Global RIM Business $ 10,731 $ 9,787 $ 33,515 $ 34,312 $ 93,320 Global Data Center Business — 4 2,576 82 3,096 Corporate and Other 825 1,953 2,527 5,434 12,813 Total restructuring costs $ 11,556 $ 11,744 $ 38,618 $ 39,828 $ 109,229 Other transformation costs for Project Matterhorn, included as a component of Restructuring and other transformation in the accompanying Condensed Consolidated Statement of Operations, by segment, for the three and nine months ended September 30, 2024 and 2023, and from the inception of Project Matterhorn through September 30, 2024, is as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, FROM THE INCEPTION OF PROJECT MATTERHORN THROUGH SEPTEMBER 30, 2024 2024 2023 2024 2023 Global RIM Business $ 10,799 $ 10,572 $ 30,143 $ 19,015 $ 62,413 Global Data Center Business 1,292 580 3,955 1,948 8,977 Corporate and Other 13,635 15,965 51,846 60,571 161,091 Total other transformation costs $ 25,726 $ 27,117 $ 85,944 $ 81,534 $ 232,481 The rollforward of the accrued restructuring costs and accrued other transformation costs, which are included as components of Accrued expenses and other current liabilities in our Condensed Consolidated Balance Sheets, for December 31, 2023 through September 30, 2024, is as follows: RESTRUCTURING OTHER TRANSFORMATION TOTAL RESTRUCTURING AND OTHER TRANSFORMATION Balance as of December 31, 2023 $ 10,731 $ 24,854 $ 35,585 Amount accrued 38,618 85,944 124,562 Payments (41,991) (96,464) (138,455) Balance as of September 30, 2024 $ 7,358 $ 14,334 $ 21,692

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended	9 Months Ended
	Sep. 30, 2024 shares	Sep. 30, 2024 shares
Trading Arrangements, by Individual
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false
Mr. Edward Greene [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		On August 22, 2024, Mr. Edward Greene, our Executive Vice President and Chief Human Resources Officer, adopted a 10b5-1 trading plan to sell shares between March 3, 2025 and August 29, 2025, including the sale of (i) 100% of the net shares to be acquired upon vesting of 3,915 gross restricted stock units and (ii) 100% of the net shares to be acquired upon vesting of 18,119 gross performance units (“PUs”), as adjusted based on actual results (collectively, the “August Trading Plan”). On September 20, 2024, Mr. Greene terminated the August Trading Plan and adopted a new 10b5-1 trading plan, mirroring the transactions outlined in the August Trading Plan and including a stock gifting transaction. Net shares are net of tax withholding. Mr. Greene’s plan will terminate on the earlier of (i) August 29, 2025 and (ii) the date that all trades under the plan are completed.
Name	Mr. Edward Greene
Title	Executive Vice President and Chief Human Resources Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	September 20, 2024
Expiration Date	August 29, 2025
Arrangement Duration	343 days
Mr. Barry Hytinen [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		On September 18, 2024, Mr. Barry Hytinen, our Executive Vice President and Chief Financial Officer, adopted a 10b5-1 trading plan to sell up to 16% of the net shares to be acquired upon vesting of 45,298 gross PUs, adjusted based on actual results. The transactions are scheduled to occur between March 3, 2025 and June 18, 2025. Net shares are net of tax withholding. Mr. Hytinen’s plan will terminate on the earlier of (i) June 18, 2025 and (ii) the date that all trades under the plan are completed.
Name	Mr. Barry Hytinen
Title	Executive Vice President and Chief Financial Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	September 18, 2024
Expiration Date	June 18, 2025
Arrangement Duration	273 days
Aggregate Available	45,298	45,298
Restricted Stock Units [Member] | Mr. Edward Greene [Member]
Trading Arrangements, by Individual
Aggregate Available	3,915	3,915
Performance Stock Units [Member] | Mr. Edward Greene [Member]
Trading Arrangements, by Individual
Aggregate Available	18,119	18,119

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2024
Accounting Policies [Abstract]
Cash and Cash Equivalents	CASH AND CASH EQUIVALENTS Cash and cash equivalents include cash on hand and cash invested in highly liquid short-term securities, which have remaining maturities at the date of purchase of less than 90 days. Cash and cash equivalents are carried at cost, which approximates fair value.
Accounts Receivable	ACCOUNTS RECEIVABLE We maintain an allowance for doubtful accounts and a credit memo reserve for estimated losses resulting from the potential inability of our customers to make required payments and potential disputes regarding billing and service issues.
Leases	LEASES We lease facilities for certain warehouses, data centers and office space. We also have land leases, including those on which certain facilities are located.
Fair Value Measurements	The level 3 valuations of the deferred purchase obligations were determined utilizing Monte-Carlo models and take into account our forecasted projections as they relate to the underlying performance of the respective businesses. The Monte-Carlo simulation model applied in assessing the fair value of the deferred purchase obligation associated with the ITRenew Transaction incorporates assumptions as to expected gross profits over the achievement period, including adjustments for the volatility of timing and amount of the associated revenue and costs, as well as discount rates that account for the risk of the arrangement and overall market risks. The Monte-Carlo simulation model applied in assessing the fair value of the deferred purchase obligation associated with the Regency Transaction incorporates assumptions as to expected revenue over the achievement period, including adjustments for volatility and timing, as well as discount rates that account for the risk of the arrangement and overall market risks. Any material change to these assumptions may result in a significantly higher or lower fair value of the related deferred purchase obligation.
Revenues	REVENUESThe costs associated with the initial movement of customer records into physical storage and certain commissions are considered costs to fulfill or obtain customer contracts (collectively, "Contract Costs"). DATA CENTER LESSOR CONSIDERATIONS Our Global Data Center Business features storage rental provided to customers at contractually specified rates over a fixed contractual period, which are accounted for in accordance with Accounting Standards Codification 842, Leases
Acquisition and Integration Costs	ACQUISITION AND INTEGRATION COSTSAcquisition and integration costs represent operating expenditures directly associated with the closing and integration activities of our business acquisitions that have closed, or are highly probable of closing, and include (i) advisory, legal and professional fees to complete business acquisitions and (ii) costs to integrate acquired businesses into our existing operations, including move, severance and system integration costs (collectively, "Acquisition and Integration Costs").
Income Taxes	INCOME TAXESWe provide for income taxes during interim periods based on our estimate of the effective tax rate for the year.
Commitments and Contingencies	We are involved in litigation from time to time in the ordinary course of business, including litigation arising from damage to customer assets in our facilities caused by fires and other natural disasters. While the outcome of litigation is inherently uncertain, we do not believe any current litigation will have a material adverse effect on our consolidated financial condition, results of operations or cash flows.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2024
Accounting Policies [Abstract]
Schedule of Allowance for Credit Loss	The rollforward of the allowance for doubtful accounts and credit memo reserves for the nine months ended September 30, 2024 is as follows: Balance as of December 31, 2023 $ 74,762 Credit memos charged to revenue 73,762 Allowance for bad debts charged to expense 37,668 Deductions and other (1) (102,002) Balance as of September 30, 2024 $ 84,190 (1) Primarily consists of the issuance of credit memos, the write-off of accounts receivable and the impact associated with currency translation adjustments.
Schedule of Operating and Financing Lease Right-of-Use Assets and Lease Liabilities	Operating and financing lease right-of-use assets and lease liabilities as of September 30, 2024 and December 31, 2023 are as follows: DESCRIPTION SEPTEMBER 30, 2024 DECEMBER 31, 2023 Assets: Operating lease right-of-use assets $ 2,591,238 $ 2,696,024 Financing lease right-of-use assets, net of accumulated depreciation (1) 367,500 304,600 Liabilities: Current Operating lease liabilities $ 315,093 $ 291,795 Financing lease liabilities (1) 50,455 39,089 Long-term Operating lease liabilities $ 2,438,905 $ 2,562,394 Financing lease liabilities (1) 363,155 310,776 (1) Financing lease right-of-use assets, current financing lease liabilities and long-term financing lease liabilities are included within Property, plant and equipment, net, Current portion of long-term debt and Long-term debt, net of current portion, respectively, within our Condensed Consolidated Balance Sheets.
Schedule of Lease Costs and Other Information	The components of the lease expense for the three and nine months ended September 30, 2024 and 2023 are as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, DESCRIPTION 2024 2023 2024 2023 Operating lease cost (1) $ 168,308 $ 172,040 $ 512,789 $ 489,153 Financing lease cost: Depreciation of financing lease right-of-use assets $ 13,907 $ 11,004 $ 36,929 $ 31,214 Interest expense for financing lease liabilities 5,593 4,843 16,031 13,600 (1) Operating lease cost, the majority of which is included in Cost of sales, includes variable lease costs of $42,785 and $120,473 for the three and nine months ended September 30, 2024, respectively, and $34,866 and $100,864 for the three and nine months ended September 30, 2023, respectively. NINE MONTHS ENDED SEPTEMBER 30, CASH PAID FOR AMOUNTS INCLUDED IN MEASUREMENT OF LEASE LIABILITIES: 2024 2023 Operating cash flows used in operating leases $ 355,509 $ 334,806 Operating cash flows used in financing leases (interest) 16,031 13,600 Financing cash flows used in financing leases 41,079 35,124 NON-CASH ITEMS: Operating lease modifications and reassessments $ 9,536 $ 65,874 New operating leases (including acquisitions and sale-leaseback transactions) 97,708 234,194
Schedule of Changes in the Carrying Value of Goodwill Attributable to Each Reportable Operating Segment	The changes in the carrying value of goodwill attributable to each reportable segment and Corporate and Other (as defined in Note 9) for the nine months ended September 30, 2024 are as follows: GLOBAL RIM BUSINESS GLOBAL DATA CENTER BUSINESS CORPORATE AND OTHER TOTAL CONSOLIDATED Goodwill balance, net of accumulated amortization, as of December 31, 2023 $ 3,911,945 $ 478,930 $ 627,037 $ 5,017,912 Tax deductible goodwill acquired during the period — — 131,790 131,790 Non-tax deductible goodwill acquired during the period — — 36,499 36,499 Fair value and other adjustments 984 (186) (186) 612 Currency effects 9,686 1,062 899 11,647 Goodwill balance, net of accumulated amortization, as of September 30, 2024 $ 3,922,615 $ 479,806 $ 796,039 $ 5,198,460 Accumulated goodwill impairment balance as of September 30, 2024 $ 132,409 $ — $ 26,011 $ 158,420
Schedule of Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis	The assets and liabilities carried at fair value measured on a recurring basis as of September 30, 2024 and December 31, 2023 are as follows: FAIR VALUE MEASUREMENTS AT SEPTEMBER 30, 2024 USING DESCRIPTION TOTAL CARRYING VALUE AT SEPTEMBER 30, 2024 QUOTED PRICES IN SIGNIFICANT OTHER SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3) (2) Money Market Funds $ 17,581 $ — $ 17,581 $ — Time Deposits 30,462 — 30,462 — Trading Securities 8,013 6,283 1,730 — Derivative Liabilities 29,824 — 29,824 — Deferred Purchase Obligations (1) 117,050 — — 117,050 FAIR VALUE MEASUREMENTS AT DECEMBER 31, 2023 USING DESCRIPTION TOTAL CARRYING VALUE AT DECEMBER 31, 2023 QUOTED PRICES IN SIGNIFICANT OTHER SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3) (2) Money Market Funds $ 66,008 $ — $ 66,008 $ — Time Deposits 15,913 — 15,913 — Trading Securities 9,952 6,149 3,803 — Derivative Assets 6,359 — 6,359 — Derivative Liabilities 5,769 — 5,769 — Deferred Purchase Obligations (1) 208,265 — — 208,265 (1) Primarily relates to the fair values of the deferred purchase obligations associated with the ITRenew Transaction (as defined in Note 3 to Notes to Consolidated Financial Statements included in our Annual Report) and the Regency Transaction (as defined in Note 3). (2) The following is a rollforward of the Level 3 liabilities presented above for December 31, 2023 through September 30, 2024: Balance as of December 31, 2023 $ 208,265 Additions 63,700 Payments (158,677) Other changes, including accretion 3,762 Balance as of September 30, 2024 $ 117,050
Schedule of Changes in Accumulated Other Comprehensive Items, Net	The changes in Accumulated other comprehensive items, net for the three and nine months ended September 30, 2024 and 2023 are as follows: THREE MONTHS ENDED SEPTEMBER 30, 2024 THREE MONTHS ENDED SEPTEMBER 30, 2023 FOREIGN DERIVATIVE FINANCIAL TOTAL FOREIGN DERIVATIVE FINANCIAL TOTAL Beginning of Period $ (471,935) $ 10,844 $ (461,091) $ (396,677) $ 14,433 $ (382,244) Other comprehensive income (loss): Foreign currency translation and other adjustments 106,861 — 106,861 (79,416) — (79,416) Change in fair value of derivative instruments — (34,281) (34,281) — 6,184 6,184 Reclassifications from accumulated other comprehensive items, net — — — — (2,527) (2,527) Total other comprehensive income (loss) 106,861 (34,281) 72,580 (79,416) 3,657 (75,759) End of Period $ (365,074) $ (23,437) $ (388,511) $ (476,093) $ 18,090 $ (458,003) NINE MONTHS ENDED SEPTEMBER 30, 2024 NINE MONTHS ENDED SEPTEMBER 30, 2023 FOREIGN DERIVATIVE FINANCIAL TOTAL FOREIGN DERIVATIVE FINANCIAL TOTAL Beginning of Period $ (373,628) $ 2,472 $ (371,156) $ (454,509) $ 12,506 $ (442,003) Other comprehensive income (loss): Foreign currency translation and other adjustments 8,554 — 8,554 (21,584) — (21,584) Change in fair value of derivative instruments — (23,381) (23,381) — 10,638 10,638 Reclassifications from accumulated other comprehensive items, net — (2,528) (2,528) — (5,054) (5,054) Total other comprehensive income (loss) 8,554 (25,909) (17,355) (21,584) 5,584 (16,000) End of Period $ (365,074) $ (23,437) $ (388,511) $ (476,093) $ 18,090 $ (458,003)
Schedule of Cost and Accumulated Amortization Associated with Contract Fulfillment Costs	Contract Costs as of September 30, 2024 and December 31, 2023 are as follows: SEPTEMBER 30, 2024 DECEMBER 31, 2023 GROSS ACCUMULATED NET GROSS ACCUMULATED NET Intake Costs asset $ 84,021 $ (40,865) $ 43,156 $ 76,150 $ (39,617) $ 36,533 Commissions asset 190,432 (72,480) 117,952 156,639 (64,279) 92,360
Schedule of Deferred Revenue Liabilities	Deferred revenue liabilities are reflected in our Condensed Consolidated Balance Sheets as follows: DESCRIPTION LOCATION IN BALANCE SHEET SEPTEMBER 30, 2024 DECEMBER 31, 2023 Deferred revenue - Current Deferred revenue $ 294,545 $ 325,665 Deferred revenue - Long-term Other Long-term Liabilities 85,795 100,770
Schedule of Revenue	Storage rental revenue associated with our Global Data Center Business for the three and nine months ended September 30, 2024 and 2023 is as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2024 2023 2024 2023 Storage rental revenue $ 150,796 $ 123,655 $ 438,221 $ 342,080
Schedule of Stock-based Compensation Expense	Stock-based compensation expense for the Employee Stock-Based Awards for the three and nine months ended September 30, 2024 and 2023 is as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2024 2023 2024 2023 Stock-based compensation expense $ 29,563 $ 18,313 $ 73,491 $ 53,195
Schedule of Acquisition and Integration Costs	Acquisition and Integration Costs for the three and nine months ended September 30, 2024 and 2023 are as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2024 2023 2024 2023 Acquisition and Integration Costs $ 11,262 $ 9,909 $ 28,573 $ 13,015
Schedule of (Loss) Gain on Disposal/Write-Down of Property, Plant and Equipment, Net	Loss (gain) on disposal/write-down of property, plant and equipment, net for the three and nine months ended September 30, 2024 and 2023 is as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2024 2023 2024 2023 (1) Loss (gain) on disposal/write-down of property, plant and equipment, net $ 5,091 $ (4,416) $ 8,270 $ (18,982) (1) The gains for the nine months ended September 30, 2023 primarily consist of a gain of approximately $18,500 associated with a sale-leaseback transaction of a facility in Singapore during the first quarter 2023. The gains recognized during 2023 are the result of our program to monetize a small portion of our industrial assets through sale and sale-leaseback transactions. The terms for these leases are consistent with the terms of our lease portfolio, which are disclosed in detail in Note 2.j. to Notes to Consolidated Financial Statements included in our Annual Report.
Schedule of Other Expense (Income), Net	Other expense (income), net for the three and nine months ended September 30, 2024 and 2023 consists of the following: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, DESCRIPTION 2024 2023 2024 2023 Foreign currency transaction losses (gains), net (1)(2) $ 46,657 $ (29,310) $ 31,291 $ 177 Debt extinguishment expense 5,417 — 5,417 — Other, net (3)(4) 34,288 13,039 42,957 67,702 Other Expense (Income), Net $ 86,362 $ (16,271) $ 79,665 $ 67,879 (1) The losses for the three and nine months ended September 30, 2024 primarily consist of the impact of changes in the exchange rate of the British pound sterling and the Euro against the United States dollar on our intercompany balances with and between certain of our subsidiaries. (2) The gains for the three months ended September 30, 2023 primarily consist of the impact of changes in the exchange rate of the British pound sterling against the United States dollar on our intercompany balances with and between certain of our subsidiaries. (3) Other, net for the three and nine months ended September 30, 2024 primarily consists of approximately $29,200 in charges associated with the agreement to purchase the remaining interest in the Web Werks JV (as defined and discussed in Note 3) as well as losses on our equity method investments and the change in value of our deferred purchase obligations. (4) Other, net for the nine months ended September 30, 2023 primarily consists of a loss of approximately $38,000 associated with the remeasurement to fair value of our previously held equity interest in the Clutter JV (as defined and discussed in Note 10) as well as losses on our equity method investments and the change in value of our deferred purchase obligations.
Schedule of Income Taxes	Our effective tax rates for the three and nine months ended September 30, 2024 and 2023 are as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2024 (1) 2023 (2) 2024 (1) 2023 (2) Effective Tax Rate 58.3 % 9.8 % 35.2 % 16.4 % (1) The primary reconciling items between the federal statutory tax rate of 21.0% and our overall effective tax rate for the three and nine months ended September 30, 2024 were the lack of tax benefits recognized for the year to date ordinary losses of certain entities, the benefits derived from the dividends paid deduction and the differences in the tax rates to which our foreign earnings are subject. In addition, we recorded gains and losses in Other expense (income), net during the period, for which there was no tax impact. (2) The primary reconciling items between the federal statutory tax rate of 21.0% and our overall effective tax rate for the three and nine months ended September 30, 2023 were the benefits derived from the dividends paid deduction and the differences in the tax rates to which our foreign earnings are subject. In addition, we recorded gains and losses in Other expense (income), net during the period, for which there was no tax impact.
Schedule of Basic and Diluted Net Income (Loss) Per Share Attributable to the Entity	The calculations of basic and diluted income (loss) per share for the three and nine months ended September 30, 2024 and 2023 are as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2024 2023 2024 2023 Net (Loss) Income $ (33,665) $ 91,391 $ 77,981 $ 158,069 Less: Net (Loss) Income Attributable to Noncontrolling Interests (45) 348 1,757 2,317 Net (Loss) Income Attributable to Iron Mountain Incorporated (utilized in numerator of Earnings Per Share calculation) $ (33,620) $ 91,043 $ 76,224 $ 155,752 Weighted-average shares—basic 293,603,000 292,148,000 293,229,000 291,805,000 Effect of dilutive potential stock options — 1,592,000 2,143,000 1,376,000 Effect of dilutive potential RSUs and PUs — 529,000 540,000 434,000 Weighted-average shares—diluted 293,603,000 294,269,000 295,912,000 293,615,000 Net (Loss) Income Per Share Attributable to Iron Mountain Incorporated: Basic $ (0.11) $ 0.31 $ 0.26 $ 0.53 Diluted $ (0.11) $ 0.31 $ 0.26 $ 0.53 Antidilutive stock options, RSUs and PUs excluded from the calculation 3,083,222 16,820 293,457 106,561

Acquisitions (Tables)

Acquisitions (Tables)	9 Months Ended
	Sep. 30, 2024
Business Combination, Asset Acquisition, and Joint Venture Formation [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	A summary of the cumulative consideration paid and the preliminary allocation of the purchase price paid for our acquisitions closed during the nine months ended September 30, 2024 is as follows: NINE MONTHS ENDED SEPTEMBER 30, 2024 Cash Paid (gross of cash acquired) $ 184,777 Deferred Purchase Obligations, Purchase Price Holdbacks and Other (1) 133,813 Total Consideration 318,590 Fair Value of Identifiable Assets Acquired (2) 212,826 Fair Value of Identifiable Liabilities Acquired (62,525) Goodwill Initially Recorded (3) $ 168,289 (1) Consists of the acquisition-date fair values of the Regency Deferred Purchase Obligation and the January 2025 Payment. (2) Assets acquired include supplier relationship intangible assets, with a total fair value of approximately $131,000 and a weighted average life of approximately 18 years. (3) Goodwill is primarily attributable to the assembled workforce, expanded market opportunities and costs and other operating synergies anticipated upon the integration of the operations of us and the acquired businesses.

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2024
Investments, All Other Investments [Abstract]
Schedule of Equity Method Investments	The carrying value and equity interest in the Frankfurt JV at September 30, 2024 and December 31, 2023 is as follows: SEPTEMBER 30, 2024 DECEMBER 31, 2023 CARRYING VALUE EQUITY INTEREST CARRYING VALUE EQUITY INTEREST Frankfurt JV $ 65,219 20 % $ 57,874 20 %

Derivative Instruments and He_2

Derivative Instruments and Hedging Activities (Tables)	9 Months Ended
	Sep. 30, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments	The fair values of derivative instruments recognized in our Condensed Consolidated Balance Sheets at September 30, 2024 and December 31, 2023, by derivative instrument, are as follows: SEPTEMBER 30, 2024 DECEMBER 31, 2023 DERIVATIVE INSTRUMENTS (1) Assets Liabilities Assets Liabilities Cash Flow Hedges (2) Interest rate swap agreements $ — $ (25,053) $ 1,601 $ (3,273) Net Investment Hedges (3) Cross-currency swap agreements — (4,771) 4,758 (2,496) (1) Our derivative assets are included as a component of (i) Prepaid expenses and other or (ii) Other within Other assets, net and our derivative liabilities are included as a component of (i) Accrued expenses and other current liabilities or (ii) Other long-term liabilities in our Condensed Consolidated Balance Sheets. As of September 30, 2024, $1,848 is included within Accrued expenses and other current liabilities and $27,976 is included within Other long-term liabilities. As of December 31, 2023, $6,359 is included within Other assets, $2,496 is included within Accrued expenses and other current liabilities and $3,273 is included within Other long-term liabilities. (2) As of September 30, 2024, cumulative net losses recorded within Accumulated other comprehensive items, net associated with our interest rate swap agreements are $23,437. (3) As of September 30, 2024, cumulative net gains recorded within Accumulated other comprehensive items, net associated with our cross-currency swap agreements are $37,955, which include $42,726 related to the excluded component of our cross-currency swap agreements.
Schedule of Gains (Losses) for Derivative Instruments	Unrealized (losses) gains recognized in Accumulated other comprehensive items, net during the three and nine months ended September 30, 2024 and 2023, by derivative instrument, are as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, DERIVATIVE INSTRUMENTS 2024 2023 2024 2023 Cash Flow Hedges Interest rate swap agreements $ (34,281) $ 6,184 $ (23,381) $ 10,638 Net Investment Hedges Cross-currency swap agreements (18,480) 5,822 (7,033) (15,685) Cross-currency swap agreements (excluded component) 4,176 5,270 12,529 16,921 (Losses) gains recognized in Net income (loss) during the three and nine months ended September 30, 2024 and 2023, by derivative instrument, are as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, DERIVATIVE INSTRUMENTS Location of (loss) gain 2024 2023 2024 2023 Cash Flow Hedges Interest rate swap agreements Interest expense $ — $ 2,527 $ 2,528 $ 5,054 Net Investment Hedges Cross-currency swap agreements (excluded component) Interest expense (4,176) (5,270) (12,529) (16,921)

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2024
Debt Disclosure [Abstract]
Schedule of Carrying Amount and Fair Value of Long-Term Debt Instruments	Long-term debt is as follows: SEPTEMBER 30, 2024 DECEMBER 31, 2023 DEBT (INCLUSIVE OF DISCOUNT) UNAMORTIZED DEFERRED FINANCING COSTS CARRYING AMOUNT FAIR VALUE DEBT (INCLUSIVE OF DISCOUNT) UNAMORTIZED DEFERRED FINANCING COSTS CARRYING AMOUNT FAIR VALUE Revolving Credit Facility (1) $ 1,005,000 $ (3,763) $ 1,001,237 $ 1,005,000 $ — $ (4,621) $ (4,621) $ — Term Loan A (1) 218,750 — 218,750 218,750 228,125 — 228,125 228,125 Term Loan B due 2026 (1) — — — — 659,298 (2,498) 656,800 659,750 Term Loan B due 2031 (1) 1,849,096 (15,462) 1,833,634 1,860,045 1,191,000 (13,026) 1,177,974 1,200,000 Virginia 3 Term Loans (2) 246,188 (3,336) 242,852 246,188 101,218 (4,641) 96,577 101,218 Virginia 4/5 Term Loans (2) 70,280 (3,483) 66,797 70,280 16,338 (5,892) 10,446 16,338 Virginia 6 Term Loans (3) 95,062 (5,106) 89,956 95,062 — — — — Australian Dollar Term Loan (2) 197,427 (336) 197,091 198,501 197,743 (482) 197,261 199,195 UK Bilateral Revolving Credit Facility (2) 187,431 (1,168) 186,263 187,431 178,239 — 178,239 178,239 GBP Notes (2) 535,518 (1,095) 534,423 527,239 509,254 (1,763) 507,491 489,108 4 7 / 8 % Notes due 2027 (2) 1,000,000 (4,266) 995,734 987,500 1,000,000 (5,332) 994,668 967,500 5 1 / 4 % Notes due 2028 (2) 825,000 (4,133) 820,867 818,813 825,000 (5,019) 819,981 800,250 5% Notes due 2028 (2) 500,000 (2,773) 497,227 491,250 500,000 (3,316) 496,684 478,750 7% Notes due 2029 (2) 1,000,000 (9,218) 990,782 1,037,500 1,000,000 (10,813) 989,187 1,027,500 4 7 / 8 % Notes due 2029 (2) 1,000,000 (7,233) 992,767 975,000 1,000,000 (8,318) 991,682 945,000 5 1 / 4 % Notes due 2030 (2) 1,300,000 (8,775) 1,291,225 1,280,500 1,300,000 (9,903) 1,290,097 1,241,500 4 1 / 2 % Notes (2) 1,100,000 (7,985) 1,092,015 1,039,500 1,100,000 (8,917) 1,091,083 995,500 5% Notes due 2032 (2) 750,000 (10,227) 739,773 721,875 750,000 (11,206) 738,794 684,375 5 5 / 8 % Notes (2) 600,000 (4,549) 595,451 595,500 600,000 (4,985) 595,015 567,000 Real Estate Mortgages, Financing Lease Liabilities and Other 611,321 (1,922) 609,399 611,321 519,907 (403) 519,504 519,907 Accounts Receivable Securitization Program 386,500 (734) 385,766 386,500 358,500 (317) 358,183 358,183 Total Long-term Debt 13,477,573 (95,564) 13,382,009 12,034,622 (101,452) 11,933,170 Less Current Portion (136,547) — (136,547) (120,670) — (120,670) Long-term Debt, Net of Current Portion $ 13,341,026 $ (95,564) $ 13,245,462 $ 11,913,952 $ (101,452) $ 11,812,500 (1) Collectively, the “Credit Agreement”. The Credit Agreement consists of a revolving credit facility (the “Revolving Credit Facility”), a term loan A facility (the “Term Loan A”) and a term loan B facility (the "Term Loan B due 2031"). The Credit Agreement also included a second term loan B facility (the "Term Loan B due 2026") until its extinguishment in August 2024. The remaining amount available for borrowing under the Revolving Credit Facility as of September 30, 2024 was $1,237,020 (which represents the maximum availability as of such date). The weighted average interest rate in effect under the Revolving Credit Facility was 7.0% as of September 30, 2024. Due to the discontinuance of the Canadian Dollar Offered Rate reference rate on June 28, 2024, the Credit Agreement was amended on June 7, 2024 to update the interest rate benchmark available for Canadian currency borrowings under our Revolving Credit Facility to the Canadian Overnight Repo Rate Average, effective July 1, 2024. All other material terms of the Revolving Credit Facility remain the same as disclosed in Note 7 to Notes to Consolidated Financial Statements included in our Annual Report. (2) Each as defined in Note 7 to Notes to Consolidated Financial Statements included in our Annual Report. (3) The fair value (Level 2 of the fair value hierarchy described at Note 2.e.) of this debt instrument approximates the carrying value as borrowings under this debt instrument are based on a current variable market interest rate. AGREEMENT MAXIMUM BORROWING OUTSTANDING BORROWINGS AS OF SEPTEMBER 30, 2024 DIRECT CONTRACTUAL INTEREST RATE UNUSED COMMITMENT FEE MATURITY DATE (1) Virginia 6 Term Loans (2) $ 210,000 $ 95,062 Iron Mountain Data Centers Virginia 6, LLC SOFR plus 2.75% 0.75% May 3, 2027 Virginia 7 Term Loans (3) 300,000 — Iron Mountain Data Centers Virginia 7, LLC SOFR plus 2.50% 0.75% April 12, 2027 (1) All obligations will become due on the specified maturity dates. Each agreement includes two one-year options that allow us to extend the initial maturity date, subject to the conditions specified in the agreements. (2) On May 3, 2024, Iron Mountain Data Centers Virginia 6, LLC, a wholly-owned subsidiary of Iron Mountain Data Centers Virginia 6/7 JV, LLC, entered into a credit agreement (the "Virginia 6 Credit Agreement"). The Virginia 6 Credit Agreement consists of a term loan facility (the "Virginia 6 Term Loans") and a letter of credit facility. The Virginia 6 Credit Agreement is secured by the equity interests and assets of Iron Mountain Data Centers Virginia 6, LLC. As of September 30, 2024, the interest rate in effect under the Virginia 6 Credit Agreement was 4.9%. (3) On April 12, 2024, Iron Mountain Data Centers Virginia 7, LLC, a wholly-owned subsidiary of Iron Mountain Data Centers Virginia 6/7 JV, LLC, entered into a credit agreement (the "Virginia 7 Credit Agreement"). The Virginia 7 Credit Agreement consists of a term loan facility and a letter of credit facility. The Virginia 7 Credit Agreement is secured by the equity interests and assets of Iron Mountain Data Centers Virginia 7, LLC.

Stockholders' Equity Matters (T

Stockholders' Equity Matters (Tables)	9 Months Ended
	Sep. 30, 2024
Equity [Abstract]
Schedule of Dividend Declared and Payments	In fiscal year 2023 and the nine months ended September 30, 2024, our board of directors declared the following dividends: DECLARATION DATE DIVIDEND RECORD DATE TOTAL PAYMENT DATE February 23, 2023 $ 0.6185 March 15, 2023 $ 180,339 April 5, 2023 May 4, 2023 0.6185 June 15, 2023 180,493 July 6, 2023 August 3, 2023 0.6500 September 15, 2023 189,730 October 5, 2023 November 2, 2023 0.6500 December 15, 2023 189,886 January 4, 2024 February 22, 2024 0.6500 March 15, 2024 190,506 April 4, 2024 May 2, 2024 0.6500 June 17, 2024 190,643 July 5, 2024 August 1, 2024 0.7150 September 16, 2024 209,776 October 3, 2024

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2024
Segment Reporting [Abstract]
Schedule of Analysis of Business Segment Information	An analysis of our business segment information and reconciliation to the accompanying Condensed Consolidated Financial Statements for the three and nine months ended September 30, 2024 and 2023 is as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2024 2023 2024 2023 Global RIM Business Total Revenues $ 1,260,358 $ 1,182,652 $ 3,721,092 $ 3,469,045 Adjusted EBITDA 568,994 516,548 1,644,004 1,493,394 Global Data Center Business Total Revenues $ 153,206 $ 127,535 $ 449,845 $ 357,873 Adjusted EBITDA 66,796 53,216 194,381 157,660 Corporate and Other Total Revenues $ 143,794 $ 77,988 $ 397,693 $ 233,542 Adjusted EBITDA (67,677) (69,802) (207,056) (214,626) Total Consolidated Total Revenues $ 1,557,358 $ 1,388,175 $ 4,568,630 $ 4,060,460 Adjusted EBITDA 568,113 499,962 1,631,329 1,436,428
Schedule of Reconciliation of Net Income (Loss) to Adjusted EBITDA	A reconciliation of Net (Loss) Income to Adjusted EBITDA on a consolidated basis for the three and nine months ended September 30, 2024 and 2023 is as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2024 2023 2024 2023 Net (Loss) Income $ (33,665) $ 91,391 $ 77,981 $ 158,069 Add/(Deduct): Interest expense, net 186,067 152,801 527,107 434,148 Provision (benefit) for income taxes 12,400 9,912 42,328 30,925 Depreciation and amortization 232,240 198,757 666,296 576,218 Acquisition and Integration Costs 11,262 9,909 28,573 13,015 Restructuring and other transformation 37,282 38,861 124,562 121,362 Loss (gain) on disposal/write-down of property, plant and equipment, net (including real estate) 5,091 (4,416) 8,270 (18,982) Other expense (income), net, excluding our share of losses (gains) from our unconsolidated joint ventures 85,532 (17,626) 76,954 58,559 Stock-based compensation expense 29,563 18,313 73,491 53,195 Our share of Adjusted EBITDA reconciling items from our unconsolidated joint ventures 2,341 2,060 5,767 9,919 Adjusted EBITDA $ 568,113 $ 499,962 $ 1,631,329 $ 1,436,428
Schedule of Revenues by Product and Service Lines by Segment	Segment revenue by product and service lines for the three and nine months ended September 30, 2024 and 2023 is as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2024 2023 2024 2023 Global RIM Business Records Management (1) $ 990,333 $ 926,424 $ 2,901,465 $ 2,693,046 Data Management (1) 127,583 128,191 390,706 388,036 Information Destruction (1)(2) 142,442 128,037 428,921 387,963 Data Center (1) — — — — Global Data Center Business Records Management (1) $ — $ — $ — $ — Data Management (1) — — — — Information Destruction (1) — — — — Data Center (1) 153,206 127,535 449,845 357,873 Corporate and Other Records Management (1) $ 41,460 $ 36,092 $ 121,528 $ 107,849 Data Management (1) — — — — Information Destruction (1)(3) 102,334 41,896 276,165 125,693 Data Center (1) — — — — Total Consolidated Records Management (1) $ 1,031,793 $ 962,516 $ 3,022,993 $ 2,800,895 Data Management (1) 127,583 128,191 390,706 388,036 Information Destruction (1)(2)(3) 244,776 169,933 705,086 513,656 Data Center (1) 153,206 127,535 449,845 357,873 (1) Each of these offerings has a component of revenue that is storage rental related and a component that is service related, except for information destruction, which does not have a storage rental component. (2) Information destruction revenue for our Global RIM Business includes secure shredding services. (3) Information destruction revenue for Corporate and Other includes product revenue from our ALM business.

Related Parties (Tables)

Related Parties (Tables)	9 Months Ended
	Sep. 30, 2024
Related Party Transactions [Abstract]
Schedule of Revenue Recognized	Revenue recognized in the accompanying Condensed Consolidated Statements of Operations under these agreements for the three and nine months ended September 30, 2024 and 2023 is as follows (approximately): THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2024 2023 2024 2023 Frankfurt JV Agreements (1) $ 200 $ — $ 2,700 $ 1,700 Clutter Agreement (2) — — — 13,000 (1) Revenue associated with the Frankfurt JV Agreements is presented as a component of our Global Data Center Business segment. (2) Revenue associated with the Clutter Agreement is presented as a component of our Global RIM Business segment.

Restructuring And Other Trans_2

Restructuring And Other Transformation (Tables)	9 Months Ended
	Sep. 30, 2024
Restructuring and Related Activities [Abstract]
Schedule of Restructuring And Other Transformation	Restructuring and other transformation related to Project Matterhorn included in the accompanying Condensed Consolidated Statement of Operations for the three and nine months ended September 30, 2024 and 2023, and from the inception of Project Matterhorn through September 30, 2024, is as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, FROM THE INCEPTION OF PROJECT MATTERHORN THROUGH SEPTEMBER 30, 2024 2024 2023 2024 2023 Restructuring $ 11,556 $ 11,744 $ 38,618 $ 39,828 $ 109,229 Other transformation 25,726 27,117 85,944 81,534 232,481 Restructuring and other transformation $ 37,282 $ 38,861 $ 124,562 $ 121,362 $ 341,710 Restructuring costs for Project Matterhorn, included as a component of Restructuring and other transformation in the accompanying Condensed Consolidated Statement of Operations, by segment, for the three and nine months ended September 30, 2024 and 2023, and from the inception of Project Matterhorn through September 30, 2024, is as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, FROM THE INCEPTION OF PROJECT MATTERHORN THROUGH SEPTEMBER 30, 2024 2024 2023 2024 2023 Global RIM Business $ 10,731 $ 9,787 $ 33,515 $ 34,312 $ 93,320 Global Data Center Business — 4 2,576 82 3,096 Corporate and Other 825 1,953 2,527 5,434 12,813 Total restructuring costs $ 11,556 $ 11,744 $ 38,618 $ 39,828 $ 109,229 Other transformation costs for Project Matterhorn, included as a component of Restructuring and other transformation in the accompanying Condensed Consolidated Statement of Operations, by segment, for the three and nine months ended September 30, 2024 and 2023, and from the inception of Project Matterhorn through September 30, 2024, is as follows: THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, FROM THE INCEPTION OF PROJECT MATTERHORN THROUGH SEPTEMBER 30, 2024 2024 2023 2024 2023 Global RIM Business $ 10,799 $ 10,572 $ 30,143 $ 19,015 $ 62,413 Global Data Center Business 1,292 580 3,955 1,948 8,977 Corporate and Other 13,635 15,965 51,846 60,571 161,091 Total other transformation costs $ 25,726 $ 27,117 $ 85,944 $ 81,534 $ 232,481 The rollforward of the accrued restructuring costs and accrued other transformation costs, which are included as components of Accrued expenses and other current liabilities in our Condensed Consolidated Balance Sheets, for December 31, 2023 through September 30, 2024, is as follows: RESTRUCTURING OTHER TRANSFORMATION TOTAL RESTRUCTURING AND OTHER TRANSFORMATION Balance as of December 31, 2023 $ 10,731 $ 24,854 $ 35,585 Amount accrued 38,618 85,944 124,562 Payments (41,991) (96,464) (138,455) Balance as of September 30, 2024 $ 7,358 $ 14,334 $ 21,692

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Allowance for Doubtful Accounts and Credit Memo Reserves (Details) - Allowance for doubtful accounts $ in Thousands	9 Months Ended
	Sep. 30, 2024 USD ($)
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	$ 74,762
Credit memos charged to revenue	73,762
Allowance for bad debts charged to expense	37,668
Deductions and other	(102,002)
Ending balance	$ 84,190

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Supplemental Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Accounting Policies [Abstract]
Operating lease right-of-use assets	$ 2,591,238	$ 2,696,024
Financing lease right-of-use assets, net of accumulated depreciation	367,500	304,600
Current
Operating lease liabilities	315,093	291,795
Finance lease liabilities	50,455	39,089
Long-term
Operating lease liabilities	2,438,905	2,562,394
Finance lease liabilities	$ 363,155	$ 310,776
Finance lease, right-of-use asset, statement of financial position [Extensible List]	Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization	Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization
Operating lease, liability, current, statement of financial position [Extensible List]	Accrued expenses and other current liabilities (includes current portion of operating lease liabilities)	Accrued expenses and other current liabilities (includes current portion of operating lease liabilities)
Finance lease, liability, current, statement of financial position [Extensible List]	Current portion of long-term debt	Current portion of long-term debt
Finance lease, liability, noncurrent, statement of financial position [Extensible List]	Long-term Debt, net of current portion	Long-term Debt, net of current portion

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Leases Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Accounting Policies [Abstract]
Operating lease cost	$ 168,308	$ 172,040	$ 512,789	$ 489,153
Depreciation of financing lease right-of-use assets	13,907	11,004	36,929	31,214
Interest expense for financing lease liabilities	5,593	4,843	16,031	13,600
Variable lease costs	$ 42,785	$ 34,866	$ 120,473	$ 100,864

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Supplemental Cash Flows (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Accounting Policies [Abstract]
Operating cash flows used in operating leases	$ 355,509	$ 334,806
Operating cash flows used in financing leases (interest)	16,031	13,600
Financing cash flows used in financing leases	41,079	35,124
Operating lease modifications and reassessments	9,536	65,874
New operating leases (including acquisitions and sale-leaseback transactions)	$ 97,708	$ 234,194

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Schedule of Changes in Carrying Value of Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2024 USD ($)
Gross amount of goodwill [Roll Forward]
Goodwill beginning balance	$ 5,017,912
Tax deductible goodwill acquired during the period	131,790
Non-tax deductible goodwill acquired during the period	36,499
Fair value and other adjustments	612
Currency effects	11,647
Goodwill ending balance	5,198,460
Accumulated goodwill impairment	158,420
GLOBAL RIM BUSINESS
Gross amount of goodwill [Roll Forward]
Goodwill beginning balance	3,911,945
Tax deductible goodwill acquired during the period	0
Non-tax deductible goodwill acquired during the period	0
Fair value and other adjustments	984
Currency effects	9,686
Goodwill ending balance	3,922,615
Accumulated goodwill impairment	132,409
GLOBAL DATA CENTER BUSINESS
Gross amount of goodwill [Roll Forward]
Goodwill beginning balance	478,930
Tax deductible goodwill acquired during the period	0
Non-tax deductible goodwill acquired during the period	0
Fair value and other adjustments	(186)
Currency effects	1,062
Goodwill ending balance	479,806
Accumulated goodwill impairment	0
CORPORATE AND OTHER
Gross amount of goodwill [Roll Forward]
Goodwill beginning balance	627,037
Tax deductible goodwill acquired during the period	131,790
Non-tax deductible goodwill acquired during the period	36,499
Fair value and other adjustments	(186)
Currency effects	899
Goodwill ending balance	796,039
Accumulated goodwill impairment	$ 26,011

Summary of Significant Accoun_9

Summary of Significant Accounting Policies - Fair Value Measurements (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Deferred Purchase Obligations
Deferred Purchase Obligations [Roll Forward]
Balance as of December 31, 2023	$ 208,265
Additions	63,700
Payments	(158,677)
Other changes, including accretion	3,762
Balance as of September 30, 2024	117,050
Fair Value, Measurements, Recurring | QUOTED PRICES IN ACTIVE MARKETS (LEVEL 1)
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Trading Securities	6,283	$ 6,149
Derivative Assets		0
Derivative Liabilities	0	0
Deferred purchase obligations	0	0
Fair Value, Measurements, Recurring | QUOTED PRICES IN ACTIVE MARKETS (LEVEL 1) | Money Market Funds
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Cash and cash equivalents	0	0
Fair Value, Measurements, Recurring | QUOTED PRICES IN ACTIVE MARKETS (LEVEL 1) | Time Deposits
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Cash and cash equivalents	0	0
Fair Value, Measurements, Recurring | SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 2)
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Trading Securities	1,730	3,803
Derivative Assets		6,359
Derivative Liabilities	29,824	5,769
Deferred purchase obligations	0	0
Fair Value, Measurements, Recurring | SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 2) | Money Market Funds
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Cash and cash equivalents	17,581	66,008
Fair Value, Measurements, Recurring | SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 2) | Time Deposits
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Cash and cash equivalents	30,462	15,913
Fair Value, Measurements, Recurring | SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3)
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Trading Securities	0	0
Derivative Assets		0
Derivative Liabilities	0	0
Deferred purchase obligations	117,050	208,265
Fair Value, Measurements, Recurring | SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3) | Money Market Funds
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Cash and cash equivalents	0	0
Fair Value, Measurements, Recurring | SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3) | Time Deposits
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Cash and cash equivalents	0	0
Fair Value, Measurements, Recurring | Estimate of Fair Value
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Trading Securities	8,013	9,952
Derivative Assets		6,359
Derivative Liabilities	29,824	5,769
Deferred purchase obligations	117,050	208,265
Fair Value, Measurements, Recurring | Estimate of Fair Value | Money Market Funds
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Cash and cash equivalents	17,581	66,008
Fair Value, Measurements, Recurring | Estimate of Fair Value | Time Deposits
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Cash and cash equivalents	$ 30,462	$ 15,913

Summary of Significant Accou_10

Summary of Significant Accounting Policies - Accumulated Other Comprehensive Income and Other Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
AOCI Rollforward
Beginning of Period	$ (132,749)	$ 416,343	$ 211,773	$ 636,793
Other comprehensive income (loss):
Foreign currency translation and other adjustments	106,861	(79,416)	8,554	(21,584)
Change in fair value of derivative instruments	(34,281)	6,184	(23,381)	10,638
Reclassifications from Accumulated Other Comprehensive Items, net	0	(2,527)	(2,528)	(5,054)
Total other comprehensive income (loss)	72,580	(75,759)	(17,355)	(16,000)
End of Period	(102,408)	262,631	(102,408)	262,631
TOTAL
AOCI Rollforward
Beginning of Period	(461,091)	(382,244)	(371,156)	(442,003)
Other comprehensive income (loss):
End of Period	(388,511)	(458,003)	(388,511)	(458,003)
FOREIGN CURRENCY TRANSLATION AND OTHER ADJUSTMENTS
AOCI Rollforward
Beginning of Period	(471,935)	(396,677)	(373,628)	(454,509)
Other comprehensive income (loss):
Foreign currency translation and other adjustments	106,861	(79,416)	8,554	(21,584)
Change in fair value of derivative instruments	0	0	0	0
Reclassifications from Accumulated Other Comprehensive Items, net	0	0	0	0
Total other comprehensive income (loss)	106,861	(79,416)	8,554	(21,584)
End of Period	(365,074)	(476,093)	(365,074)	(476,093)
DERIVATIVE FINANCIAL INSTRUMENTS
AOCI Rollforward
Beginning of Period	10,844	14,433	2,472	12,506
Other comprehensive income (loss):
Foreign currency translation and other adjustments	0	0	0	0
Change in fair value of derivative instruments	(34,281)	6,184	(23,381)	10,638
Reclassifications from Accumulated Other Comprehensive Items, net	0	(2,527)	(2,528)	(5,054)
Total other comprehensive income (loss)	(34,281)	3,657	(25,909)	5,584
End of Period	$ (23,437)	$ 18,090	$ (23,437)	$ 18,090

Summary of Significant Accou_11

Summary of Significant Accounting Policies - Contract Fulfillment Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Intake Costs asset
Contract With Customer, Asset And Liabilities [Line Items]
GROSS CARRYING AMOUNT	$ 84,021	$ 76,150
ACCUMULATED AMORTIZATION	(40,865)	(39,617)
NET CARRYING AMOUNT	43,156	36,533
Commissions asset
Contract With Customer, Asset And Liabilities [Line Items]
GROSS CARRYING AMOUNT	190,432	156,639
ACCUMULATED AMORTIZATION	(72,480)	(64,279)
NET CARRYING AMOUNT	$ 117,952	$ 92,360

Summary of Significant Accou_12

Summary of Significant Accounting Policies - Summary of Deferred Revenue Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Accounting Policies [Abstract]
Deferred revenue - Current	$ 294,545	$ 325,665
Deferred revenue - Long-term	$ 85,795	$ 100,770

Summary of Significant Accou_13

Summary of Significant Accounting Policies - Storage Rental (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Lessor, Lease, Description [Line Items]
Storage rental revenue	$ 1,557,358	$ 1,388,175	$ 4,568,630	$ 4,060,460
GLOBAL DATA CENTER BUSINESS
Lessor, Lease, Description [Line Items]
Storage rental revenue	153,206	127,535	449,845	357,873
Storage rental
Lessor, Lease, Description [Line Items]
Storage rental revenue	935,701	858,656	2,740,289	2,499,501
Storage rental | GLOBAL DATA CENTER BUSINESS
Lessor, Lease, Description [Line Items]
Storage rental revenue	$ 150,796	$ 123,655	$ 438,221	$ 342,080

Summary of Significant Accou_14

Summary of Significant Accounting Policies - Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Employee Stock-Based Awards
Stock-based compensation expense	$ 29,563	$ 18,313	$ 73,491	$ 53,195
Stock options granted (in shares)			83,100
Unrecognized compensation cost	$ 78,844		$ 78,844
Restricted Stock Units
Employee Stock-Based Awards
Granted (in shares)			670,900
Performance units
Employee Stock-Based Awards
Granted (in shares)			453,000

Summary of Significant Accou_15

Summary of Significant Accounting Policies - Acquisition and Integration costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Accounting Policies [Abstract]
Acquisition and Integration Costs	$ 11,262	$ 9,909	$ 28,573	$ 13,015

Summary of Significant Accou_16

Summary of Significant Accounting Policies - Loss (Gain) on Disposal/Write-Down of Property, Plant and Equipment, Net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Accumulated Other Comprehensive Income (Loss) [Line Items]
Loss (gain) on disposal/write-down of property, plant and equipment, net	$ 5,091	$ (4,416)	$ 8,270	$ (18,982)
Facilities in Singapore
Accumulated Other Comprehensive Income (Loss) [Line Items]
Sale and sale-leaseback transactions				$ 18,500

Summary of Significant Accou_17

Summary of Significant Accounting Policies - Other Expense (Income), Net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Accumulated Other Comprehensive Income (Loss) [Line Items]
Foreign currency transaction losses (gains), net	$ 46,657	$ (29,310)	$ 31,291	$ 177
Debt extinguishment expense	5,417	0	5,417	0
Other, net	34,288	13,039	42,957	67,702
Other Expense (Income), Net	86,362	$ (16,271)	79,665	67,879
Web Werks JV
Accumulated Other Comprehensive Income (Loss) [Line Items]
Loss associated with the Clutter Acquisition	$ 29,200		$ 29,200
Clutter JV
Accumulated Other Comprehensive Income (Loss) [Line Items]
Loss associated with the Clutter Acquisition				$ 38,000

Summary of Significant Accou_18

Summary of Significant Accounting Policies - Income Taxes (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Accounting Policies [Abstract]
Effective tax rate	58.30%	9.80%	35.20%	16.40%
Federal statutory tax rate	21%	21%	21%	21%

Summary of Significant Accou_19

Summary of Significant Accounting Policies - Income (Loss) Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Income (Loss) Per Share-Basic and Diluted
Net (Loss) Income	$ (33,665)	$ 91,391	$ 77,981	$ 158,069
Less: Net (Loss) Income Attributable to Noncontrolling Interests	(45)	348	1,757	2,317
Net (Loss) Income Attributable to Iron Mountain Incorporated (utilized in numerator of Earnings Per Share calculation)	$ (33,620)	$ 91,043	$ 76,224	$ 155,752
Weighted-average shares—basic (in shares)	293,603,000	292,148,000	293,229,000	291,805,000
Effect of dilutive potential stock options (in shares)	0	1,592,000	2,143,000	1,376,000
Effect of dilutive potential RSUs and PUs (in shares)	0	529,000	540,000	434,000
Weighted-average shares—diluted (in shares)	293,603,000	294,269,000	295,912,000	293,615,000
Net Income (Loss) Per Share Attributable to Iron Mountain Incorporated:
Basic (in dollars per share)	$ (0.11)	$ 0.31	$ 0.26	$ 0.53
Diluted (in dollars per share)	$ (0.11)	$ 0.31	$ 0.26	$ 0.53
Antidilutive stock options, RSUs and PUs, excluded from the calculation (in shares)	3,083,222	16,820	293,457	106,561

Acquisitions - Additional Infor

Acquisitions - Additional Information (Details) € in Thousands, ₨ in Thousands

1 Months Ended

3 Months Ended

9 Months Ended

Sep. 20, 2024 USD ($)

Sep. 20, 2024 EUR (€)

Jul. 05, 2024 USD ($)

Jul. 05, 2024 INR (₨)

Jan. 03, 2024 USD ($)

Mar. 31, 2025 USD ($)

Mar. 31, 2025 INR (₨)

Jan. 31, 2025 USD ($)

Sep. 30, 2024 USD ($)

Sep. 30, 2024 USD ($)

Sep. 30, 2023 USD ($)

Sep. 20, 2024 EUR (€)

Jul. 01, 2024

Business Acquisition [Line Items]

Cash paid for acquisitions, net of cash acquired

$ 174,445,000

$ 33,932,000

Web Werks JV

Business Acquisition [Line Items]

EQUITY INTEREST

71.94%

71.94%

Forecast | Web Werks JV

Business Acquisition [Line Items]

EQUITY INTEREST

28.06%

28.06%

Wisetek

Business Acquisition [Line Items]

Ownership acquired

100%

100%

Total Consideration

$ 51,900,000

€ 46,600

Contingent consideration liability

$ 4,700,000

€ 4,200

RSR Partners, LLC

Business Acquisition [Line Items]

Ownership acquired

100%

Total Consideration

$ 200,000,000

Cash Paid (gross of cash acquired)

125,000,000

RSR Partners, LLC | Regency Deferred Purchase Obligation

Business Acquisition [Line Items]

Contingent consideration liability

78,400,000

Value of possible subsequent acquisition, low

0

Value of possible subsequent acquisition, high

$ 200,000,000

RSR Partners, LLC | Forecast

Business Acquisition [Line Items]

Cash Paid (gross of cash acquired)

$ 75,000,000

Web Werks JV

Business Acquisition [Line Items]

Ownership acquired

8.55%

8.55%

36.61%

Total Consideration

$ 35,000,000

₨ 3,000,000

Cash paid for acquisitions, net of cash acquired

$ 29,200,000

Web Werks JV | Forecast

Business Acquisition [Line Items]

Total Consideration

$ 11,900,000

₨ 1,000,000

Cash Paid (gross of cash acquired)

$ 114,600,000

₨ 9,600,000

Acquisitions - Schedule of Purc

Acquisitions - Schedule of Purchase Price Allocation (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Business Acquisition [Line Items]
Goodwill initially recorded	$ 5,198,460	$ 5,017,912
Year To Date Acquisitions
Business Acquisition [Line Items]
Cash Paid (gross of cash acquired)	184,777
Deferred Purchase Obligations, Purchase Price Holdbacks and Other	133,813
Total Consideration	318,590
Fair Value of Identifiable Assets Acquired	212,826
Fair Value of Identifiable Liabilities Acquired	(62,525)
Goodwill initially recorded	168,289
Customer Relationships | Year To Date Acquisitions
Business Acquisition [Line Items]
Customer and supplier relationship intangible assets	$ 131,000
Acquired finite-lived intangible assets, weighted average useful life	18 years

Investments - Schedule of Equit

Investments - Schedule of Equity Method Investments (Details) - Frankfurt JV - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Schedule of Equity Method Investments [Line Items]
CARRYING VALUE	$ 65,219	$ 57,874
EQUITY INTEREST	20%	20%

Derivative Instruments and He_3

Derivative Instruments and Hedging Activities - Additional Information (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Interest rate swap agreements
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount	$ 1,354,000	$ 520,000
Cross-currency Swap Agreements | Net Investment Hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount	$ 509,200	$ 509,200

Derivative Instruments and He_4

Derivative Instruments and Hedging Activities - Net Assets (Liabilities) (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative asset, current	$ 1,848
Derivative asset, noncurrent		$ 6,359
Derivative liability, noncurrent	$ 27,976	3,273
Derivative liability, current		2,496
Derivative liability, statement of financial position [Extensible Enumeration]	Accrued expenses and other current liabilities (includes current portion of operating lease liabilities), Other Long-term Liabilities
Derivative asset, current, statement of financial position [Extensible Enumeration]	Prepaid expenses and other
Derivative liability, noncurrent, statement of financial position [Extensible Enumeration]	Other Long-term Liabilities
Derivative asset, statement of financial position [Extensible Enumeration]	Prepaid expenses and other, Assets, Noncurrent, Excluding Property, Plant and Equipment, Net
Derivative asset, noncurrent, statement of financial position [Extensible Enumeration]	Assets, Noncurrent, Excluding Property, Plant and Equipment, Net
Interest rate swap agreements
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Cumulative net gain in AOCI	$ (23,437)
Cash Flow Hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Assets	0	1,601
Derivative Liabilities	(25,053)	(3,273)
Net Investment Hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Assets	0	4,758
Derivative Liabilities	(4,771)	$ (2,496)
Cumulative net gain in cross-currency swaps	37,955
Net Investment Hedges | Cross-currency swap agreements (excluded component)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Cumulative net gain in cross-currency swaps	$ 42,726

Derivative Instruments and He_5

Derivative Instruments and Hedging Activities - Unrealized Gains (Losses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Interest rate swap agreements
Derivative [Line Items]
Interest rate swap agreements	$ 0	$ 2,527	$ 2,528	$ 5,054
Cross-currency swap agreements | Net Investment Hedges
Derivative [Line Items]
Cross-currency swap agreements (excluded component)	(4,176)	(5,270)	(12,529)	(16,921)
Designated as Hedging Instrument | Interest rate swap agreements
Derivative [Line Items]
Interest rate swap agreements	(34,281)	6,184	(23,381)	10,638
Designated as Hedging Instrument | Cross-currency swap agreements
Derivative [Line Items]
Cross-currency swap agreements	(18,480)	5,822	(7,033)	(15,685)
Not Designated as Hedging Instrument | Cross-currency swap agreements
Derivative [Line Items]
Cross-currency swap agreements	$ 4,176	$ 5,270	$ 12,529	$ 16,921

Debt - Carrying Amount and Fair

Debt - Carrying Amount and Fair Value of Long-Term Debt Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
DEBT (INCLUSIVE OF DISCOUNT)	$ 13,477,573	$ 12,034,622
UNAMORTIZED DEFERRED FINANCING COSTS	(95,564)	(101,452)
CARRYING AMOUNT	13,382,009	11,933,170
Debt, current portion	(136,547)	(120,670)
Unamortized debt issuance expense, net of current portion	0	0
Carrying amount, current maturities	(136,547)	(120,670)
Long term debt, gross, net of current portion	13,341,026	11,913,952
Unamortized deferred financing costs, noncurrent	(95,564)	(101,452)
Carrying amount, excluding current maturities	13,245,462	11,812,500
Accounts Receivable Securitization Program
Debt Instrument [Line Items]
DEBT (INCLUSIVE OF DISCOUNT)	386,500	358,500
UNAMORTIZED DEFERRED FINANCING COSTS	(734)	(317)
CARRYING AMOUNT	385,766	358,183
FAIR VALUE	386,500	358,183
Credit Agreement | Revolving Credit Facility
Debt Instrument [Line Items]
DEBT (INCLUSIVE OF DISCOUNT)	1,005,000
UNAMORTIZED DEFERRED FINANCING COSTS	(3,763)
CARRYING AMOUNT	1,001,237
FAIR VALUE	1,005,000
Remaining capacity	$ 1,237,020
Weighted average interest rate (as a percent)	7%
Credit Agreement | Revolving Credit Facility, Netting
Debt Instrument [Line Items]
DEBT (INCLUSIVE OF DISCOUNT)		0
UNAMORTIZED DEFERRED FINANCING COSTS		(4,621)
CARRYING AMOUNT		(4,621)
FAIR VALUE		0
Credit Agreement | UK Bilateral Revolving Credit Facility
Debt Instrument [Line Items]
DEBT (INCLUSIVE OF DISCOUNT)	$ 187,431	178,239
UNAMORTIZED DEFERRED FINANCING COSTS	(1,168)	0
CARRYING AMOUNT	186,263	178,239
FAIR VALUE	187,431	178,239
Term Loan Facility | Term Loan A
Debt Instrument [Line Items]
DEBT (INCLUSIVE OF DISCOUNT)	218,750	228,125
UNAMORTIZED DEFERRED FINANCING COSTS	0	0
CARRYING AMOUNT	218,750	228,125
FAIR VALUE	218,750	228,125
Term Loan Facility | Term Loan B due 2026
Debt Instrument [Line Items]
DEBT (INCLUSIVE OF DISCOUNT)	0	659,298
UNAMORTIZED DEFERRED FINANCING COSTS	0	(2,498)
CARRYING AMOUNT	0	656,800
FAIR VALUE	0	659,750
Term Loan Facility | Term Loan B due 2031
Debt Instrument [Line Items]
DEBT (INCLUSIVE OF DISCOUNT)	1,849,096	1,191,000
UNAMORTIZED DEFERRED FINANCING COSTS	(15,462)	(13,026)
CARRYING AMOUNT	1,833,634	1,177,974
FAIR VALUE	1,860,045	1,200,000
Term Loan Facility | Virginia 3 Term Loans
Debt Instrument [Line Items]
DEBT (INCLUSIVE OF DISCOUNT)	246,188	101,218
UNAMORTIZED DEFERRED FINANCING COSTS	(3,336)	(4,641)
CARRYING AMOUNT	242,852	96,577
FAIR VALUE	246,188	101,218
Term Loan Facility | Virginia 4/5 Term Loans
Debt Instrument [Line Items]
DEBT (INCLUSIVE OF DISCOUNT)	70,280	16,338
UNAMORTIZED DEFERRED FINANCING COSTS	(3,483)	(5,892)
CARRYING AMOUNT	66,797	10,446
FAIR VALUE	70,280	16,338
Term Loan Facility | Virginia 6 Term Loan
Debt Instrument [Line Items]
DEBT (INCLUSIVE OF DISCOUNT)	95,062	0
UNAMORTIZED DEFERRED FINANCING COSTS	(5,106)	0
CARRYING AMOUNT	89,956	0
FAIR VALUE	$ 95,062	0
Stated interest rate (as a percent)	4.90%
Australian Dollar Term Loan
Debt Instrument [Line Items]
DEBT (INCLUSIVE OF DISCOUNT)	$ 197,427	197,743
UNAMORTIZED DEFERRED FINANCING COSTS	(336)	(482)
CARRYING AMOUNT	197,091	197,261
FAIR VALUE	198,501	199,195
Senior Notes | GBP Notes
Debt Instrument [Line Items]
DEBT (INCLUSIVE OF DISCOUNT)	535,518	509,254
UNAMORTIZED DEFERRED FINANCING COSTS	(1,095)	(1,763)
CARRYING AMOUNT	534,423	507,491
FAIR VALUE	527,239	489,108
Senior Notes | 47/8% Notes due 2027
Debt Instrument [Line Items]
DEBT (INCLUSIVE OF DISCOUNT)	1,000,000	1,000,000
UNAMORTIZED DEFERRED FINANCING COSTS	(4,266)	(5,332)
CARRYING AMOUNT	995,734	994,668
FAIR VALUE	$ 987,500	967,500
Stated interest rate (as a percent)	4.875%
Senior Notes | 51/4% Notes due 2028
Debt Instrument [Line Items]
DEBT (INCLUSIVE OF DISCOUNT)	$ 825,000	825,000
UNAMORTIZED DEFERRED FINANCING COSTS	(4,133)	(5,019)
CARRYING AMOUNT	820,867	819,981
FAIR VALUE	$ 818,813	800,250
Stated interest rate (as a percent)	5.25%
Senior Notes | 5% Notes due 2028
Debt Instrument [Line Items]
DEBT (INCLUSIVE OF DISCOUNT)	$ 500,000	500,000
UNAMORTIZED DEFERRED FINANCING COSTS	(2,773)	(3,316)
CARRYING AMOUNT	497,227	496,684
FAIR VALUE	$ 491,250	478,750
Stated interest rate (as a percent)	5%
Senior Notes | 7% Notes due 2029
Debt Instrument [Line Items]
DEBT (INCLUSIVE OF DISCOUNT)	$ 1,000,000	1,000,000
UNAMORTIZED DEFERRED FINANCING COSTS	(9,218)	(10,813)
CARRYING AMOUNT	990,782	989,187
FAIR VALUE	$ 1,037,500	1,027,500
Stated interest rate (as a percent)	7%
Senior Notes | 47/8% Notes due 2029
Debt Instrument [Line Items]
DEBT (INCLUSIVE OF DISCOUNT)	$ 1,000,000	1,000,000
UNAMORTIZED DEFERRED FINANCING COSTS	(7,233)	(8,318)
CARRYING AMOUNT	992,767	991,682
FAIR VALUE	$ 975,000	945,000
Stated interest rate (as a percent)	4.875%
Senior Notes | 51/4% Notes due 2030
Debt Instrument [Line Items]
DEBT (INCLUSIVE OF DISCOUNT)	$ 1,300,000	1,300,000
UNAMORTIZED DEFERRED FINANCING COSTS	(8,775)	(9,903)
CARRYING AMOUNT	1,291,225	1,290,097
FAIR VALUE	$ 1,280,500	1,241,500
Stated interest rate (as a percent)	5.25%
Senior Notes | 41/2% Notes
Debt Instrument [Line Items]
DEBT (INCLUSIVE OF DISCOUNT)	$ 1,100,000	1,100,000
UNAMORTIZED DEFERRED FINANCING COSTS	(7,985)	(8,917)
CARRYING AMOUNT	1,092,015	1,091,083
FAIR VALUE	$ 1,039,500	995,500
Stated interest rate (as a percent)	4.50%
Senior Notes | 5% Notes due 2032
Debt Instrument [Line Items]
DEBT (INCLUSIVE OF DISCOUNT)	$ 750,000	750,000
UNAMORTIZED DEFERRED FINANCING COSTS	(10,227)	(11,206)
CARRYING AMOUNT	739,773	738,794
FAIR VALUE	$ 721,875	684,375
Stated interest rate (as a percent)	5%
Senior Notes | 55/8% Notes
Debt Instrument [Line Items]
DEBT (INCLUSIVE OF DISCOUNT)	$ 600,000	600,000
UNAMORTIZED DEFERRED FINANCING COSTS	(4,549)	(4,985)
CARRYING AMOUNT	595,451	595,015
FAIR VALUE	$ 595,500	567,000
Stated interest rate (as a percent)	5.625%
Real Estate Mortgages, Financing Lease Liabilities and Other
Debt Instrument [Line Items]
DEBT (INCLUSIVE OF DISCOUNT)	$ 611,321	519,907
UNAMORTIZED DEFERRED FINANCING COSTS	(1,922)	(403)
CARRYING AMOUNT	609,399	519,504
FAIR VALUE	$ 611,321	$ 519,907

Debt - Narrative (Details)

Debt - Narrative (Details)		1 Months Ended	3 Months Ended	6 Months Ended
	Jul. 02, 2024 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2024 USD ($) Agreement	Jun. 30, 2024 USD ($)	Sep. 30, 2024 GBP (£)	Aug. 19, 2024 USD ($)	Jun. 14, 2024 USD ($)	Dec. 31, 2023 USD ($)
Debt Instrument [Line Items]
Number of new agreements | Agreement			2
Outstanding borrowing		$ 13,477,573,000	$ 13,477,573,000					$ 12,034,622,000
Term Loan Facility
Debt Instrument [Line Items]
Payment of debt costs	$ 4,300,000
Credit Agreement
Debt Instrument [Line Items]
Letters of credit outstanding		79,530,000	79,530,000
Credit Agreement | Revolving Credit Facility
Debt Instrument [Line Items]
Outstanding borrowing		1,005,000,000	1,005,000,000
Letters of credit outstanding		7,980,000	7,980,000
Term Loan B due 2031 | Term Loan Facility
Debt Instrument [Line Items]
Maximum borrowing amount	$ 1,806,700,000			$ 1,194,000,000		$ 1,860,000,000
Contractual interest rate	2%			2.25%
Periodic payment		4,700,000
Outstanding borrowing		1,849,096,000	1,849,096,000					1,191,000,000
Term Loan B due 2026 | Term Loan Facility
Debt Instrument [Line Items]
Maximum borrowing amount	$ 53,400,000			$ 656,300,000
Outstanding borrowing		0	0					659,298,000
Accounts Receivable Securitization Program
Debt Instrument [Line Items]
Maximum borrowing amount		400,000,000	400,000,000				$ 360,000,000
Line of credit facility, accordion feature, increase limit							$ 450,000,000
Outstanding borrowing		$ 386,500,000	$ 386,500,000					$ 358,500,000
Average interest rate (as a percent)		5.90%	5.90%		5.90%
UK Bilateral Revolving Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing amount | £					£ 140,000,000
Line of credit facility, accordion feature, increase limit | £					£ 125,000,000
Stated interest rate (as a percent)		7%	7%		7%

Debt - Credit Agreement (Detail

Debt - Credit Agreement (Details)	9 Months Ended
	Sep. 30, 2024 USD ($) extension	Dec. 31, 2023 USD ($)
Debt Instrument [Line Items]
Outstanding borrowing	$ 13,477,573,000	$ 12,034,622,000
Term Loan Facility
Debt Instrument [Line Items]
Number of extensions | extension	2
Period of extension	1 year
Virginia 6 Term Loan | Term Loan Facility
Debt Instrument [Line Items]
Maximum borrowing amount	$ 210,000,000
Outstanding borrowing	$ 95,062,000	$ 0
Contractual interest rate	2.75%
Unused commitment fee (percent)	0.75%
Stated interest rate (as a percent)	4.90%
Virginia 7 Term Loan | Term Loan Facility
Debt Instrument [Line Items]
Maximum borrowing amount	$ 300,000,000
Outstanding borrowing	$ 0
Contractual interest rate	2.50%
Unused commitment fee (percent)	0.75%

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Thousands	Sep. 30, 2024 USD ($)
Insurance settlement
Commitments and Contingencies
Reasonably possible additional losses	$ 14,000

Stockholders' Equity Matters (D

Stockholders' Equity Matters (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended							9 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023
Equity [Abstract]
Dividend per share (in dollars per share)	$ 0.7150	$ 0.6500	$ 0.6500	$ 0.6500	$ 0.6500	$ 0.6185	$ 0.6185
TOTAL AMOUNT	$ 211,463				$ 188,889			$ 598,098	$ 554,274
Dividends, Common Stock, Cash	$ 209,776	$ 190,643	$ 190,506	$ 189,886	$ 189,730	$ 180,493	$ 180,339

Stockholders' Equity Matters -

Stockholders' Equity Matters - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
	Nov. 06, 2024	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023
Debt Instrument [Line Items]
Dividend per share (in dollars per share)		$ 0.7150	$ 0.6500	$ 0.6500	$ 0.6500	$ 0.6500	$ 0.6185	$ 0.6185
Noncontrolling Interests		$ 156,605			$ 125
Iron Mountain Data Centers Virginia 4/5 JV, LP
Debt Instrument [Line Items]
Noncontrolling Interests		53,400
Iron Mountain Data Centers Virginia 6/7 JV, LLC
Debt Instrument [Line Items]
Noncontrolling Interests		$ 103,100
Subsequent Event
Debt Instrument [Line Items]
Dividend per share (in dollars per share)	$ 0.715

Segment Information - Segment R

Segment Information - Segment Reporting Information by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Segment Reporting Information [Line Items]
Total Revenues	$ 1,557,358	$ 1,388,175	$ 4,568,630	$ 4,060,460
Adjusted EBITDA	568,113	499,962	1,631,329	1,436,428
Global RIM Business
Segment Reporting Information [Line Items]
Total Revenues	1,260,358	1,182,652	3,721,092	3,469,045
Adjusted EBITDA	568,994	516,548	1,644,004	1,493,394
Global Data Center Business
Segment Reporting Information [Line Items]
Total Revenues	153,206	127,535	449,845	357,873
Adjusted EBITDA	66,796	53,216	194,381	157,660
Corporate and Other
Segment Reporting Information [Line Items]
Total Revenues	143,794	77,988	397,693	233,542
Adjusted EBITDA	$ (67,677)	$ (69,802)	$ (207,056)	$ (214,626)

Segment Information - Reconcili

Segment Information - Reconciliation to of Net Income to Adjusted EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Reconciliation to of Net Income to Adjusted EBITDA
Net Income (Loss)	$ (33,665)	$ 91,391	$ 77,981	$ 158,069
Interest expense, net	186,067	152,801	527,107	434,148
Provision (benefit) for income taxes	12,400	9,912	42,328	30,925
Depreciation and amortization	232,240	198,757	666,296	576,218
Acquisition and Integration Costs	11,262	9,909	28,573	13,015
Restructuring and other transformation	37,282	38,861	124,562	121,362
Loss (gain) on disposal/write-down of property, plant and equipment, net (including real estate)	5,091	(4,416)	8,270	(18,982)
Other expense (income), net, excluding our share of losses (gains) from our unconsolidated joint ventures	85,532	(17,626)	76,954	58,559
Stock-based compensation expense	29,563	18,313	73,491	53,195
Our share of Adjusted EBITDA reconciling items from our unconsolidated joint ventures	2,341	2,060	5,767	9,919
Adjusted EBITDA	$ 568,113	$ 499,962	$ 1,631,329	$ 1,436,428

Segment Information - Revenues

Segment Information - Revenues by Product and Service Lines by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Segment Reporting Information [Line Items]
Total Revenues	$ 1,557,358	$ 1,388,175	$ 4,568,630	$ 4,060,460
GLOBAL RIM BUSINESS
Segment Reporting Information [Line Items]
Total Revenues	1,260,358	1,182,652	3,721,092	3,469,045
GLOBAL DATA CENTER BUSINESS
Segment Reporting Information [Line Items]
Total Revenues	153,206	127,535	449,845	357,873
CORPORATE AND OTHER
Segment Reporting Information [Line Items]
Total Revenues	143,794	77,988	397,693	233,542
Records Management
Segment Reporting Information [Line Items]
Total Revenues	1,031,793	962,516	3,022,993	2,800,895
Records Management | GLOBAL RIM BUSINESS
Segment Reporting Information [Line Items]
Total Revenues	990,333	926,424	2,901,465	2,693,046
Records Management | GLOBAL DATA CENTER BUSINESS
Segment Reporting Information [Line Items]
Total Revenues	0	0	0	0
Records Management | CORPORATE AND OTHER
Segment Reporting Information [Line Items]
Total Revenues	41,460	36,092	121,528	107,849
Data Management
Segment Reporting Information [Line Items]
Total Revenues	127,583	128,191	390,706	388,036
Data Management | GLOBAL RIM BUSINESS
Segment Reporting Information [Line Items]
Total Revenues	127,583	128,191	390,706	388,036
Data Management | GLOBAL DATA CENTER BUSINESS
Segment Reporting Information [Line Items]
Total Revenues	0	0	0	0
Data Management | CORPORATE AND OTHER
Segment Reporting Information [Line Items]
Total Revenues	0	0	0	0
Information Destruction
Segment Reporting Information [Line Items]
Total Revenues	244,776	169,933	705,086	513,656
Information Destruction | GLOBAL RIM BUSINESS
Segment Reporting Information [Line Items]
Total Revenues	142,442	128,037	428,921	387,963
Information Destruction | GLOBAL DATA CENTER BUSINESS
Segment Reporting Information [Line Items]
Total Revenues	0	0	0	0
Information Destruction | CORPORATE AND OTHER
Segment Reporting Information [Line Items]
Total Revenues	102,334	41,896	276,165	125,693
Data Center
Segment Reporting Information [Line Items]
Total Revenues	153,206	127,535	449,845	357,873
Data Center | GLOBAL RIM BUSINESS
Segment Reporting Information [Line Items]
Total Revenues	0	0	0	0
Data Center | GLOBAL DATA CENTER BUSINESS
Segment Reporting Information [Line Items]
Total Revenues	153,206	127,535	449,845	357,873
Data Center | CORPORATE AND OTHER
Segment Reporting Information [Line Items]
Total Revenues	$ 0	$ 0	$ 0	$ 0

Related Parties (Details)

Related Parties (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Related Party Transaction [Line Items]
Total Revenues	$ 1,557,358	$ 1,388,175	$ 4,568,630	$ 4,060,460
Co-venturer | Frankfurt JV Agreements
Related Party Transaction [Line Items]
Total Revenues	200	0	2,700	1,700
Co-venturer | Clutter Agreement
Related Party Transaction [Line Items]
Total Revenues	$ 0	$ 0	$ 0	$ 13,000

Restructuring And Other Trans_3

Restructuring And Other Transformation - Additional Information (Details) $ in Thousands	Sep. 30, 2024 USD ($)
Project Matterhorn
Restructuring Cost and Reserve [Line Items]
Expected cost	$ 150

Restructuring And Other Trans_4

Restructuring And Other Transformation - Restructuring Charges (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		25 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024
Restructuring Cost and Reserve [Line Items]
Restructuring and other transformation	$ 37,282	$ 38,861	$ 124,562	$ 121,362
Project Matterhorn
Restructuring Cost and Reserve [Line Items]
Restructuring	11,556	11,744	38,618	39,828	$ 109,229
Other transformation	25,726	27,117	85,944	81,534	232,481
Restructuring and other transformation	37,282	38,861	124,562	121,362	341,710
Project Matterhorn | GLOBAL RIM BUSINESS
Restructuring Cost and Reserve [Line Items]
Restructuring	10,731	9,787	33,515	34,312	93,320
Other transformation	10,799	10,572	30,143	19,015	62,413
Project Matterhorn | GLOBAL DATA CENTER BUSINESS
Restructuring Cost and Reserve [Line Items]
Restructuring	0	4	2,576	82	3,096
Other transformation	1,292	580	3,955	1,948	8,977
Project Matterhorn | CORPORATE AND OTHER
Restructuring Cost and Reserve [Line Items]
Restructuring	825	1,953	2,527	5,434	12,813
Other transformation	$ 13,635	$ 15,965	$ 51,846	$ 60,571	$ 161,091

Restructuring and Other Trans_5

Restructuring and Other Transformation - Restructuring Rollforward (Details) - Project Matterhorn $ in Thousands	9 Months Ended
	Sep. 30, 2024 USD ($)
Restructuring Reserve [Roll Forward]
Beginning balance	$ 35,585
Amount accrued	124,562
Payments	(138,455)
Ending balance	21,692
RESTRUCTURING
Restructuring Reserve [Roll Forward]
Beginning balance	10,731
Amount accrued	38,618
Payments	(41,991)
Ending balance	7,358
OTHER TRANSFORMATION
Restructuring Reserve [Roll Forward]
Beginning balance	24,854
Amount accrued	85,944
Payments	(96,464)
Ending balance	$ 14,334