CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($)	Mar. 31, 2018	Dec. 31, 2017	[1]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	53,496,889	53,400,281
Common stock, shares outstanding (in shares)	53,496,889	53,400,281
Convertible Notes Payable
Stated interest rate	3.75%	3.75%
Face amount of the Notes	$ 143,750,000	$ 143,750,000

[1] Derived from the audited December 31, 2017 financial statements