Additional Financial Statement Information - Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Paid During the Year For
Interest, Net of Amount Capitalized	$ 270	$ 346	$ 327
Income Taxes Paid, Net	172	121	236
Non-Cash Financing and Investing Activities
Increase in Capital Lease Obligations	$ 14	$ 0	$ 5

The increase during the period in capital lease obligations due to entering into new capital leases.

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The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.

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Amount of cash paid for interest, excluding capitalized interest, classified as operating activity. Includes, but is not limited to, payment to settle zero-coupon bond for accreted interest of debt discount and debt instrument with insignificant coupon interest rate in relation to effective interest rate of borrowing attributable to accreted interest of debt discount.

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