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Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions | 6 Months Ended |
--- | --- | ---
Jun. 30, 2019 | Jan. 01, 2019
New Accounting Pronouncements |  |
Length of fiscal quarters, weeks | 91 days |
Operating lease liability | $ 1,352 |
Operating lease, right-of-use asset | $ 1,280 |
ASC Topic 842 - Leases |  |
New Accounting Pronouncements |  |
Operating lease liability |  | $ 1,400
Operating lease, right-of-use asset |  | $ 1,400

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