Balance Sheet Parenthetical (Parentheticals) - $ / shares	Jun. 30, 2017	Dec. 31, 2016
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	65,927,104	65,704,568
Preferred stock, par value	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	50,000,000	50,000,000
Preferred Stock, Shares Issued	0	0
Treasury shares, at cost	64,024	28,763