Summary Of Significant Accounting Policies - Long-Lived Assets (Details)	12 Months Ended
Dec. 31, 2017
Equipment, furniture and other \| Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	1 year
Equipment, furniture and other \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Building and improvements
Property, Plant and Equipment [Line Items]
Estimated useful life	30 years

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

No definition available.

Name:	us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration