Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Allowance for trade accounts receivable	$ 2,029	$ 2,670
Unamortized premium on notes	818	956
Deferred debt costs	$ 24,321	$ 9,704
Preferred stock, par value (dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Common stock, par value (dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	80,000,000	80,000,000
Common stock, shares issued	43,500,032	43,500,032
Common stock, shares outstanding	42,758,940	42,196,680
Treasury stock, shares	741,092	1,303,352