Basis of Presentation and Significant Accounting Policies - Narrative (Detail) $ in Thousands	3 Months Ended	9 Months Ended
	Mar. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2020 USD ($)	Jan. 08, 2020 data_center	Jan. 01, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Effective income tax rate, continuing operations		24.70%	27.90%
Adjustments due to adoption of ASU 2016-13	$ 8,669,294	$ 10,555,966	$ 8,761,031	$ 10,388,258			$ 8,840,382	$ 8,749,229	$ 8,424,788	$ 7,219,279
Allowance for doubtful accounts		15,429					13,026
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustments due to adoption of ASU 2016-13	1,509,317	$ 1,709,308	$ 1,266,430	$ 1,642,621			1,391,425	$ 1,145,580	$ 1,002,053	889,948
Accounting Standards Update 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for doubtful accounts						$ 900
COVID-19
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Payments for one-time bonus and compensation costs COVID-19	$ 8,600
Cumulative adjustment due to adoption of ASU
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustments due to adoption of ASU 2016-13							(900)			(5,973)
Cumulative adjustment due to adoption of ASU | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustments due to adoption of ASU 2016-13						$ (900)	$ (900)			$ (5,973)
Axtel
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Data centers purchased | data_center					3