Summary of Significant Accounting Policies - Gain on Disposal/Write-Down of Property, Plant and Equipment, (net) (Details) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2019 USD ($) facility	Jun. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on disposal/write-down of property, plant and equipment, net	$ 9,284		$ 388	$ 17,087	$ 2,064
Gain associated with a sale-leaseback transaction	$ 9,800
Number of facilities | facility	5
United Kingdom | Disposed of by sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of real estate, net of tax		$ 36,000
North American Records and Information Management Business
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on disposal/write-down of property, plant and equipment, net				(3,100)
Iron Mountain Iron Cloud
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on disposal/write-down of property, plant and equipment, net	$ (800)			$ (24,800)