Significant Accounting Policies Narrative (Details) $ in Millions	3 Months Ended
Jun. 30, 2018 segment	Mar. 31, 2018 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of reportable segments \| segment	3
ASU 2016-16
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting pronouncement \| $		$ 152

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.

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