Commitments and Contingencies - Additional Information (Details) $ in Millions	1 Months Ended	12 Months Ended
	Jul. 31, 2007 shares	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Commitments And Contingencies Disclosure [Line Items]
Non-cancelable operating lease expiration period		2021
Rent expense | $		$ 0.3	$ 0.3	$ 0.3
Lawsuit filing date		November 6, 2017
Number of options granted | shares	350,000
Claims description		The Contractors claim that our subsequent one-for-five and one-for-17 reverse stock splits should not apply to their option awards.
Reverse stock split, description		one-for-five and one-for-17 reverse stock splits
Option One
Commitments And Contingencies Disclosure [Line Items]
Reverse stock split, conversion ratio		0.2
Option Two
Commitments And Contingencies Disclosure [Line Items]
Reverse stock split, conversion ratio		0.0588