Debt and Line of Credit - Narrative (Details) - USD ($)		12 Months Ended
	Apr. 12, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Aug. 30, 2019	Mar. 03, 2016
Line of Credit Facility and Term Loan [Line Items]
Incurred and capitalized direct cost		$ 244,000	$ 463,000	$ 157,000
Line of credit		107,140,000	58,363,000
Credit And Security Agreement 2018
Line of Credit Facility and Term Loan [Line Items]
Letters of credit outstanding amount		200,000
Line of Credit | Credit And Security Agreement 2018
Line of Credit Facility and Term Loan [Line Items]
Line of credit facility, maximum borrowing capacity	$ 125,000		40,000,000		$ 144,300,000
Line of credit facility, remaining borrowing capacity		36,960,000
Incurred and capitalized direct cost			$ 294,000
Deferred loan costs, current	1,229,000	808,000
Line of Credit | Credit And Security Agreement 2016
Line of Credit Facility and Term Loan [Line Items]
Loss on deferred loan costs	243,000
Write off of deferred debt issuance cost	521,000
Line of Credit | Credit And Security Agreement 2018, First Amendment
Line of Credit Facility and Term Loan [Line Items]
Incurred and capitalized direct cost		170,000
Line of Credit | Credit And Security Agreement 2018, Second Amendment
Line of Credit Facility and Term Loan [Line Items]
Line of credit facility, maximum borrowing capacity	$ 136,800
Incurred and capitalized direct cost		40,000
Line of Credit | Credit And Security Agreement 2018, Third Amendment
Line of Credit Facility and Term Loan [Line Items]
Line of credit facility, maximum borrowing capacity		144,300
Incurred and capitalized direct cost		$ 204,000
Line of Credit | Minimum | Credit And Security Agreement 2018
Line of Credit Facility and Term Loan [Line Items]
Interest rate, stated percentage	0.175%
Line of Credit | Maximum | Credit And Security Agreement 2018
Line of Credit Facility and Term Loan [Line Items]
Interest rate, stated percentage	0.275%
Line of Credit | Base Rate | Minimum | Credit And Security Agreement 2018
Line of Credit Facility and Term Loan [Line Items]
Interest rate, stated percentage	0.25%
Line of Credit | Base Rate | Maximum | Credit And Security Agreement 2018
Line of Credit Facility and Term Loan [Line Items]
Interest rate, stated percentage	1.375%
Line of Credit | Eurodollar | Minimum | Credit And Security Agreement 2018
Line of Credit Facility and Term Loan [Line Items]
Interest rate, stated percentage	1.25%
Line of Credit | Eurodollar | Maximum | Credit And Security Agreement 2018
Line of Credit Facility and Term Loan [Line Items]
Interest rate, stated percentage	2.375%
Term Loan | Credit And Security Agreement 2016
Line of Credit Facility and Term Loan [Line Items]
Line of credit facility, maximum borrowing capacity						$ 85,000
Term Loan | Credit And Security Agreement 2018, First Amendment
Line of Credit Facility and Term Loan [Line Items]
Line of credit facility, maximum borrowing capacity	$ 40,000					25,000
Term Loan | Credit And Security Agreement 2018, Second Amendment
Line of Credit Facility and Term Loan [Line Items]
Line of credit facility, maximum borrowing capacity						11,800
Term Loan | Credit And Security Agreement 2018, Third Amendment
Line of Credit Facility and Term Loan [Line Items]
Line of credit facility, maximum borrowing capacity						$ 19,300