Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Property and equipment, accumulated depreciation and amortization	$ 494,121	$ 432,510
Intangible assets, accumulated amortization	$ 30,222	$ 28,400
Special preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Special preferred stock, shares issued	3	3
Special preferred stock, shares outstanding	3	3
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares outstanding	53,426,475	53,401,439