Recent Accounting Pronouncements (Details) - USD ($) $ in Millions	Jun. 30, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, liability	$ 401
Operating lease, right-of-use asset	$ 361
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, liability		$ 383
Operating lease, right-of-use asset		$ 343