Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Millions	Sep. 30, 2019	Jan. 01, 2019
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Operating lease right of use assets	$ 62
Operating lease liabilities	$ 78
ASU 2016-02
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Operating lease right of use assets		$ 68
Operating lease liabilities		$ 80