Consolidated Statements Of Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
REVENUE	$ 198,037	$ 202,874	$ 240,458
EXPENSES:
Depreciation and amortization	121,023	121,598	139,754
Cost of sales	304	475	464
Selling, general and administrative	29,799	25,971	29,088
Total operating expenses	151,126	148,044	169,306
INCOME FROM OPERATIONS	46,911	54,830	71,152
Interest expense	(25,222)	(28,213)	(29,143)
Interest income	193	362	132
Foreign currency exchange gains (losses)	(1,974)	(2,222)	681
Loss on early extinguishment of debt	0	(1,504)	0
Gain on sale of marketable securities	0	0	230
Other income	63	488	780
Income before income taxes	19,971	23,741	43,832
Provision (benefit) for income taxes	10,293	(89,940)	6,782
NET INCOME	$ 9,678	$ 113,681	$ 37,050