Income Taxes - Net Deferred Tax Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Net deferred tax assets
Net deferred tax assets	$ 22,400	$ 25,058

Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b),(c)
-URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32537-109319

Name:	us-gaap_DeferredTaxAssetsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant