Supplemental Guarantors Consolidating Condensed Financial Information (Statement of Income) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Condensed Financial Statements, Captions [Line Items]
REVENUE	$ 57,053	$ 51,351
EXPENSES:
Depreciation and amortization	37,858	29,338
Cost of sales	126	39
Selling, general and administrative	7,425	7,387
Total operating expenses	45,409	36,764
INCOME (LOSS) FROM OPERATIONS	11,644	14,587
Interest expense, net	(6,207)	(9,315)
Foreign currency exchange gains (losses)	(1,274)	(647)
Loss on early extinguishment of debt	0	(1,504)
Other income (loss)	(14)	1
Income (loss) before income taxes and equity in income (loss) of subsidiaries	4,149	3,122
Provision (benefit) for income taxes	2,257	1,384
Equity in income (loss) of subsidiaries	0	0
NET INCOME	1,892	1,738
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
REVENUE	0	0
EXPENSES:
Depreciation and amortization	0	0
Cost of sales	0	0
Selling, general and administrative	311	285
Total operating expenses	311	285
INCOME (LOSS) FROM OPERATIONS	(311)	(285)
Interest expense, net	(5,232)	(7,831)
Foreign currency exchange gains (losses)	0	0
Loss on early extinguishment of debt		(1,504)
Other income (loss)	(14)
Income (loss) before income taxes and equity in income (loss) of subsidiaries	(5,557)	(9,620)
Provision (benefit) for income taxes	0	0
Equity in income (loss) of subsidiaries	7,449	11,358
NET INCOME	1,892	1,738
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
REVENUE	39,918	33,120
EXPENSES:
Depreciation and amortization	24,137	18,009
Cost of sales	114	38
Selling, general and administrative	4,771	4,463
Total operating expenses	29,022	22,510
INCOME (LOSS) FROM OPERATIONS	10,896	10,610
Interest expense, net	(527)	(1,065)
Foreign currency exchange gains (losses)	3	0
Loss on early extinguishment of debt		0
Other income (loss)	0	1
Income (loss) before income taxes and equity in income (loss) of subsidiaries	10,372	9,546
Provision (benefit) for income taxes	2,360	484
Equity in income (loss) of subsidiaries	(578)	2,296
NET INCOME	7,434	11,358
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
REVENUE	17,481	18,575
EXPENSES:
Depreciation and amortization	13,736	11,329
Cost of sales	12	1
Selling, general and administrative	2,689	2,983
Total operating expenses	16,437	14,313
INCOME (LOSS) FROM OPERATIONS	1,044	4,262
Interest expense, net	(448)	(419)
Foreign currency exchange gains (losses)	(1,277)	(647)
Loss on early extinguishment of debt		0
Other income (loss)	0	0
Income (loss) before income taxes and equity in income (loss) of subsidiaries	(681)	3,196
Provision (benefit) for income taxes	(103)	900
Equity in income (loss) of subsidiaries	0	0
NET INCOME	(578)	2,296
Consolidating Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
REVENUE	(346)	(344)
EXPENSES:
Depreciation and amortization	(15)	0
Cost of sales	0	0
Selling, general and administrative	(346)	(344)
Total operating expenses	(361)	(344)
INCOME (LOSS) FROM OPERATIONS	15	0
Interest expense, net	0	0
Foreign currency exchange gains (losses)	0	0
Loss on early extinguishment of debt		0
Other income (loss)	0	0
Income (loss) before income taxes and equity in income (loss) of subsidiaries	15	0
Provision (benefit) for income taxes	0	0
Equity in income (loss) of subsidiaries	(6,871)	(13,654)
NET INCOME	$ (6,856)	$ (13,654)