Related Party Transactions (Details) - USD ($) $ in Thousands		3 Months Ended							6 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Related Party Transaction [Line Items]
Property management fee, percent fee													7.50%
Management Fee		$ 12,611	$ 12,503		$ 12,293	$ 12,207	$ 12,031	$ 11,989		$ 24,020	$ 37,238	$ 36,227	$ 49,837		$ 48,520		$ 46,946
Direct Costs of Leased and Rented Property or Equipment, Related Party	[1]	$ 10,880	$ 10,721		$ 11,512	$ 10,163	$ 9,700	9,606		19,306	32,210	30,478	43,281		40,981		36,655
Contribution (Distribution) from/to Member				$ (105,472)				$ (108,573)	$ (177,586)	$ (183,436)	$ (278,231)	$ (278,242)	$ (362,759)	[2]	(367,976)	[2],[3]	$ (335,034)	[2],[3]
Previously outstanding 2012 secured notes tranche A [Member] | 2012 Secured Notes [Member]
Related Party Transaction [Line Items]
Previously outstanding Debt Instrument, Interest Rate, Stated Percentage																	2.381%
Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Percentage of Towers Where Land is Owned by Related Party													30.00%
Members' Capital [Member]
Related Party Transaction [Line Items]
Contribution (Distribution) from/to Member	[2]												$ (126,082)		$ (152,459)		$ (159,985)

[1] Exclusive of depreciation, amortization and accretion shown separately and certain indirect costs included in the management fee.

[2] The Company receives no cash from, and is not party to, the CCIC transactions described in note 2.

[3] The Company receives no cash from, and is not party to, the CCIC transactions described in note 2. Such transactions, however, are reflected on the cash flow statement for GAAP purposes as if an amount equal to the lease component for such transactions had been received by the Company, and as such, the amounts have been recorded as fixed assets (in the form of permanent improvements) and deferred revenues.