Summary of Accounting Policies (Goodwill and Other Intangible Assets Narrative) (Details)	12 Months Ended
Dec. 31, 2017
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, estimated useful lives	3 years
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, estimated useful lives	30 years

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_FiniteLivedIntangibleAssetsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration