Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash Flows from Operating Activities:
Net Income	$ 95	$ 128
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	320	301
Non-cash compensation expense attributable to stock awards	48	47
Loss on modification and extinguishment of debt	44	0
Accretion of debt discount and amortization of debt issuance costs	5	5
Accrued interest on long-term debt, net	(28)	23
Deferred income taxes	62	81
Other, net	(5)	(9)
Changes in working capital items:
Receivables	6	(44)
Other current assets	(32)	(35)
Accounts payable	42	48
Deferred revenue	50	46
Other current liabilities	(68)	(81)
Net Cash Provided by Operating Activities	539	510
Cash Flows from Investing Activities:
Capital expenditures	(368)	(297)
Change in restricted cash and securities, net	0	(828)
Net Cash Used in Investing Activities	(368)	(1,125)
Cash Flows from Financing Activities:
Long-term debt borrowings, net of issuance costs	4,569	765
Payments on and repurchases of long-term debt and capital leases	(4,613)	(1)
Net Cash (Used in) Provided by Financing Activities	(44)	764
Effect of Exchange Rates on Cash and Cash Equivalents	1	1
Net Change in Cash and Cash Equivalents	128	150
Cash and Cash Equivalents at Beginning of Period	1,819	854
Cash and Cash Equivalents at End of Period	1,947	1,004
Supplemental Disclosure of Cash Flow Information:
Cash interest paid	153	112
Income taxes paid, net of refunds	$ 10	$ 7