Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
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)	10,455,934	9,119,058
Common stock, shares outstanding (in shares)	7,159,645	5,889,013
Treasury stock, shares (in shares)	3,296,289	3,230,045
Series D preferred stock
Preferred stock, par value (in $ per share)	$ 0.01	$ 0
Preferred stock, shares authorized (in shares)	1,150,000	0
Preferred stock, shares issued (in shares)	1,150,000	0
Preferred stock, shares outstanding (in shares)	1,150,000	0