Equity - Additional Information (Details) - USD ($) $ / shares in Units, shares in Thousands		12 Months Ended
	Oct. 27, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stockholders' Equity Note [Abstract]
Net proceeds from rights offering	$ 89,867,000	$ 89,867,000	$ 0	$ 0
Rights offering, net (in shares)	5,000
Exercise price (in dollars per share)	$ 18.00