Basis of Presentation and Significant Accounting Policies - Narrative (Detail) - center	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Nov. 02, 2020	Oct. 01, 2020	Jan. 08, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Effective income tax rate, continuing operations	17.30%	20.20%
Bell Data Centers
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Data centers purchased			1	12
Axtel
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Data centers purchased					3