Restructuring Expense (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Activity in accrued restructuring expense
Accrued restructuring, beginning of the period		$ 497,000	$ 15,000
Provision for restructuring charges	$ 2,085,000		1,349,000
Cash payments	(1,803,000)	$ (497,000)	(867,000)
Accrued restructuring, end of the period	282,000		$ 497,000
Impairment of right-of-use assets	1,328,000
Exit of an office facility
Activity in accrued restructuring expense
Impairment of right-of-use assets	1,300,000
Write-off of fixed assets	$ 170,000