Condensed Consolidated Statement of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities:
Net income (loss)	$ 210	$ 114
Adjustments to reconcile net income (loss) to net cash provided by (used for) operating activities:
Depreciation, amortization and accretion	394	374
(Gains) losses on retirement of long-term obligations	1	71
Amortization of Debt Issuance Costs and Discounts	1	2
Stock-based compensation expense	29	23
Asset write-down charges	6	3
Deferred income tax (benefit) provision	1	1
Other non-cash adjustments	2	2
Changes in assets and liabilities, excluding the effects of acquisitions:
Increase (decrease) in accrued interest	(41)	(28)
Increase (decrease) in accounts payable	(5)	(5)
Increase (decrease) in other liabilities	(24)	(57)
Decrease (increase) in receivables	(43)	(5)
Decrease (increase) in other assets	(19)	(43)
Net cash provided by (used for) operating activities	512	452
Cash flows from investing activities:
Payments for acquisitions, net of cash acquired	(10)	(14)
Capital expenditures	(480)	(370)
Other investing activities, net	1	0
Net cash provided by (used for) investing activities	(489)	(384)
Cash flows from financing activities:
Proceeds from issuance of long-term debt	996	1,743
Principal payments on debt and other long-term obligations	(25)	(32)
Purchases and redemptions of long-term debt	(12)	(1,318)
Borrowings under revolving credit facility	710	170
Payments under revolving credit facility	(1,140)	(1,050)
Payments for financing costs	(10)	(15)
Net proceeds from issuance of common stock	0	843
Purchases of Common Stock	(42)	(33)
Dividends/distributions paid on common stock	(477)	(443)
Dividends paid on preferred stock	(28)	(28)
Net cash provided by (used for) financing activities	(28)	(163)
Net increase (decrease) in cash, cash equivalents, and restricted cash	(5)	(95)
Cash and Cash Equivalents at Beginning of Period	413	440
Cash and Cash Equivalents at End of Period	408	345
Effect of Exchange Rate on Cash and Cash Equivalents [Abstract]
Effect of exchange rate changes	$ 0	$ 0