CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2018	Dec. 31, 2017
CONSOLIDATED BALANCE SHEETS
Common stock and paid in capital, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock and paid in capital, shares authorized	370,100,000	370,100,000
Common stock and paid in capital, shares issued	284,380,175	284,213,685
Common stock and paid in capital, shares outstanding	284,380,175	284,213,685