Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Jun. 30, 2018	Dec. 31, 2017
Common stock, par value (in $ per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)	10,523,050	10,455,934
Common stock, shares outstanding (in shares)	7,166,139	7,159,645
Treasury stock, shares (in shares)	3,356,911	3,296,289
Series D convertible preferred stock
Preferred stock, par value (in $ per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	1,150,000	1,150,000
Preferred stock, shares issued (in shares)	1,150,000	1,150,000
Preferred stock, shares outstanding (in shares)	1,150,000	1,150,000