XML 48 R34.htm IDEA: XBRL DOCUMENT v3.19.2
Fair Value Disclosures (Estimated Fair Values and Carrying Amounts of Assets and Liabilities) (Details) - USD ($)
$ in Millions
Jun. 30, 2019
Dec. 31, 2018
Fair Value Disclosures [Abstract]    
Cash and cash equivalents, at carrying value $ 288 $ 277
Cash and cash equivalents, fair value   277
Restricted cash, current and non-current, carrying value 141 136
Restricted cash, current and non-current, fair value   136
Long-term debt and other obligations, carrying amount 17,569 16,682
Long-term debt and other obligations, fair value $ 18,351 $ 16,562