Commitments and Contingencies - Narrative (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) facility	Sep. 30, 2016 USD ($)
Long-term Purchase Commitment [Line Items]
Number of leased facilities | facility			2
Rent expense	$ 74,000	$ 72,000	$ 221,000	$ 218,000
Penalty for not meeting minimum requirements			0
Colorado
Long-term Purchase Commitment [Line Items]
Letters of credit outstanding, amount	18,000		18,000
Colorado | Wells Fargo Bank, N.A.
Long-term Purchase Commitment [Line Items]
Letters of credit outstanding, amount	$ 18,000		$ 18,000