Condensed Consolidated Statement of Cash Flows - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Cash and Cash Equivalents at Beginning of Period	[1]	$ 440	$ 697
Cash and Cash Equivalents at End of Period	[1]	345	325
Cash flows from operating activities:
Net income (loss)		114	119
Adjustments to reconcile net income (loss) to net cash provided by (used for) operating activities:
Depreciation, amortization and accretion		374	289
(Gains) losses on retirement of long-term obligations		71	4
Amortization of deferred financing costs and other non-cash interest		2	2
Stock-based compensation expense		23	22
Asset write-down charges		3	1
Deferred income tax (benefit) provision		1	0
Other non-cash adjustments		2	(3)
Changes in assets and liabilities, excluding the effects of acquisitions:
Increase (decrease) in accrued interest		(28)	(13)
Increase (decrease) in accounts payable		(5)	(30)
Increase (decrease) in deferred revenues, deferred ground lease payables, other accrued liabilities and other liabilities		(57)	(17)
Decrease (increase) in receivables		(5)	93
Decrease (increase) in prepaid expenses, deferred site rental receivables, long-term prepaid rent and other assets		(43)	(25)
Net cash provided by (used for) operating activities		452	442
Cash flows from investing activities:
Payment for acquisitions of businesses, net of cash acquired		(14)	(1,497)
Capital expenditures		(370)	(262)
Other investing activities, net		0	(4)
Net cash provided by (used for) investing activities		(384)	(1,763)
Cash flows from financing activities:
Proceeds from issuance of long-term debt		1,743	998
Principal payments on long-term debt and other long-term obligations		(32)	(29)
Purchases and redemptions of long-term debt		(1,318)	0
Borrowings under revolving credit facility		170	1,405
Payments under revolving credit facility		(1,050)	(1,070)
Payments for financing costs		(15)	(7)
Proceeds from Issuance of Common Stock		843	22
Purchases of capital stock		(33)	(22)
Dividends/distributions paid on common stock		(443)	(348)
Dividends/distributions paid on preferred stock		(28)	0
Net cash provided by (used for) financing activities		(163)	949
Net increase (decrease) in cash, cash equivalents, and restricted cash		(95)	(372)
Effect of Exchange Rate on Cash and Cash Equivalents [Abstract]
Effect of exchange rate changes on cash		$ 0	$ 0

[1] See "Recently Adopted Accounting Pronouncements" in note 2 to the condensed consolidated financial statements for a discussion of recently adopted restricted cash guidance, which impacted certain presentations on the condensed consolidated statement of cash flows.