Recent Accounting Pronouncements Adoption of ASU 2016-02 (Details) - USD ($) $ in Millions	Jun. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset	$ 209		$ 0
Operating Lease, Liability	$ 223
Accounting Standards Update 2016-02 [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset		$ 223
Operating Lease, Liability		$ 240