Summary of Significant Accounting Policies Leases (Details) $ in Millions	Sep. 30, 2019 USD ($)
Minimum
Significant Accounting Policies [Line Items]
Operating lease, Right-of-use Asset	$ 122
Operating Lease, Liability	143
Maximum
Significant Accounting Policies [Line Items]
Operating lease, Right-of-use Asset	156
Operating Lease, Liability	$ 183