Employee Retirement Plan (Details) - USD ($)	1 Months Ended	12 Months Ended
Jan. 31, 2019	Jan. 31, 2019	Dec. 31, 2018	Jan. 31, 2018
Employee Retirement Plan
Matching contribution percent (up to)	50.00%		100.00%
Maximum contribution as a percent of participant compensation	4.00%		4.00%
Defined contribution plan, cost recognized		$ 483,000		$ 524,000

Amount of cost for defined contribution plan.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 70
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942

Name:	us-gaap_DefinedContributionPlanCostRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration