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Accounting Principles and Practices - Schedule of Changes to Balance Sheet for New Accounting Standards (Details) - USD ($) $ in Millions | Mar. 31, 2019 | Jan. 01, 2019 | Dec. 31, 2018
--- | --- | --- | ---
Assets |  |  |
Operating lease right-of-use assets | $ 993 |  |
Other non-current assets | 509 |  | $ 448
Liabilities |  |  |
Other current liabilities | 1,220 |  | 936
Non-current operating lease liabilities | 978 |  |
Other non-current liabilities | $ 973 |  | 1,097
Accounting Standards Update 2016-02 |  |  |
Assets |  |  |
Operating lease right-of-use assets |  | $ 1,100 |
Operating lease right-of-use assets |  |  |
Assets |  |  |
Operating lease right-of-use assets |  | 1,021 |
Operating lease right-of-use assets | Accounting Standards Update 2016-02 |  |  |
Assets |  |  |
Operating lease right-of-use assets |  | 1,021 |
Other non-current assets |  |  |
Assets |  |  |
Other non-current assets |  | 526 | 448
Other non-current assets | Accounting Standards Update 2016-02 |  |  |
Assets |  |  |
Other non-current assets |  | 78 |
Other current liabilities |  |  |
Liabilities |  |  |
Other current liabilities |  | 1,155 | 936
Other current liabilities | Accounting Standards Update 2016-02 |  |  |
Liabilities |  |  |
Other current liabilities |  | 219 |
Non-current operating lease liabilities |  |  |
Liabilities |  |  |
Non-current operating lease liabilities |  | 1,014 |
Non-current operating lease liabilities | Accounting Standards Update 2016-02 |  |  |
Liabilities |  |  |
Non-current operating lease liabilities |  | 1,014 |
Other non-current liabilities |  |  |
Liabilities |  |  |
Other non-current liabilities |  | 963 | $ 1,097
Other non-current liabilities | Accounting Standards Update 2016-02 |  |  |
Liabilities |  |  |
Other non-current liabilities |  | $ (134) |

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