Recent Accounting Pronouncements (Details) - USD ($) $ in Millions	Mar. 31, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, right-of-use assets	$ 422
Operating lease, liability	$ 530
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, right-of-use assets		$ 458
Operating lease, liability		$ 574