Debt (Secured Tower Revenue Securities) (Narrative) (Details) - USD ($)	9 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Debt instrument, principal amount	$ 12,438,000,000	$ 12,396,000,000
2014-2C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, principal amount	$ 620,000,000	620,000,000
Debt instrument, maturity date	Oct. 08, 2024
2018-1C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, principal amount	$ 640,000,000	640,000,000
Debt instrument, interest rate, stated percentage	3.448%
Debt instrument, maturity date	Mar. 09, 2023
2019-1C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, principal amount	$ 1,165,000,000	1,165,000,000
Debt instrument, interest rate, stated percentage	2.836%
Debt instrument, maturity date	Jan. 12, 2025
2020-1C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, principal amount	$ 750,000,000	750,000,000
Debt instrument, interest rate, stated percentage	1.884%
Debt instrument, maturity date	Jan. 09, 2026
2020-2C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, principal amount	$ 600,000,000	600,000,000
Debt instrument, interest rate, stated percentage	2.328%
Debt instrument, maturity date	Jan. 11, 2028
2021-1C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, principal amount	$ 1,165,000,000	1,165,000,000
Debt instrument, interest rate, stated percentage	1.631%
Debt instrument, maturity date	Nov. 09, 2026
2021-2C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, principal amount	$ 895,000,000	895,000,000
Debt instrument, interest rate, stated percentage	1.84%
Debt instrument, maturity date	Apr. 09, 2027
2021-3C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, principal amount	$ 895,000,000	$ 895,000,000
Debt instrument, interest rate, stated percentage	2.593%
Debt instrument, maturity date	Oct. 09, 2031