Operations and summary of significant accounting policies Operations and summary of significant accounting polices (Details 5 - lease accounting) $ in Millions	Jan. 01, 2019 USD ($)
Operations and summary of significant accounting policies
Expected amount, Right-of-Use asset under operating leases	$ 750
Expected amount, operating lease liability	750
Expected impact from adoption of new Lease Accounting guidance related to derecognition of assets for a Sale Lease Back transaction that qualifies for sale accounting under the new guidance	135
Expected impact from adoption of new Lease Accounting guidance related to derecognition of debt obligations for a Sale Lease Back transaction that qualifies for sale accounting under the new guidance	$ 360