Summary of Significant Accounting Policies (Details) - Segment	9 Months Ended	12 Months Ended
Sep. 30, 2017	Dec. 31, 2016
Summary of Significant Accounting Policies [Abstract]
Number of reportable segments	1	2
Percentage of decline on cost of securities treated as other-than-temporary impairment	20.00%
Period of decline on the cost of equity securities that will be considered other-than-temporary impairment	1 year

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

No definition available.

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration