Earnings Per Share (Narrative) (Details) $ in Millions	Sep. 30, 2018 USD ($)
Earnings Per Share Reconciliation [Abstract]
Remaining authorized amount under share repurchases	$ 916

Amount remaining of a stock repurchase plan authorized.

No definition available.

Name:	us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant