Summary of Significant Accounting Policies (Details 3) $ in Millions	Jan. 01, 2019 USD ($)
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle
Expected amount, Right-of-Use Assets and Lease Liabilities, under operating leases	$ 20
Accounting Standards Update 2018-02
New Accounting Pronouncements or Change in Accounting Principle
Expected amount, Reclassification of certain tax effects from AOCI to Retained Earnings	$ 97

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