Commitments and Contingencies (Details)	3 Months Ended
Mar. 31, 2018 USD ($)
Commitments and Contingencies.
Settlement amount	$ 0

Amount of judgment or settlement awarded to (against) the entity in respect of litigation.

No definition available.

Name:	us-gaap_LitigationSettlementAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration