CONSOLIDATED BALANCE SHEETS (unaudited) (Parentheticals) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Accumulated depreciation	$ 129,206	$ 134,786
Preferred stock, par value per share (in dollars per share)	$ 0.01000	$ 0.01000
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value per share (in dollars per share)	$ 0.01000	$ 0.01000
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	123,138,000	121,645,000
Common stock, shares outstanding	123,138,000	121,645,000