Condensed Consolidated Statements of Cash Flows (Parenthetical) - shares shares in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Condensed Consolidated Statements of Cash Flows
Issuance of shares of common stock to fund the Company's 401(k) matching contribution	86,828	158,717

Number of shares issued pursuant to the terms of a deferred compensation arrangement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (l)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

Name:	us-gaap_DeferredCompensationArrangementWithIndividualSharesIssued
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration