Summary of Accounting Policies - New Accounting Pronouncements (Narrative) (Details) $ in Millions	Jan. 01, 2019 USD ($)
ASU 2014-09
Redeemable Noncontrolling Interest [Line Items]
Cumulative effect	$ 1
ASU 2016-16
Redeemable Noncontrolling Interest [Line Items]
Cumulative effect	$ 1

Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant