Supplemental Guarantors Consolidating Condensed Financial Information (Statement of Operations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Condensed Financial Statements, Captions [Line Items]
REVENUE	$ 46,028	$ 35,545	$ 118,575	$ 95,041
EXPENSES:
Depreciation and amortization	29,837	23,246	69,221	65,660
Cost of sales	151	39	248	55
Selling, general and administrative	7,705	7,925	15,797	15,490
Total operating expenses	37,693	31,210	85,266	81,205
INCOME (LOSS) FROM OPERATIONS	8,335	4,335	33,309	13,836
Interest expense, net	(7,253)	(10,265)	(14,472)	(20,424)
Foreign currency exchange losses	(426)	225	(15)	457
Gain on sale of marketable securities	230	980	230	2,467
Other income	402	115	483	164
Income (loss) before income taxes and equity in income of subsidiaries	1,288	(4,610)	19,535	(3,500)
Provision for income taxes	18	416	3,559	1,015
Equity in income of subsidiaries			0	0
NET INCOME (LOSS)	1,270	(5,026)	15,976	(4,515)
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			1,174	1,042
Total operating expenses			1,174	1,042
INCOME (LOSS) FROM OPERATIONS			(1,174)	(1,042)
Interest expense, net			(5,374)	(10,146)
Foreign currency exchange losses			0	0
Gain on sale of marketable securities			0	0
Other income			1	2
Income (loss) before income taxes and equity in income of subsidiaries			(6,547)	(11,186)
Provision for income taxes			0	0
Equity in income of subsidiaries			22,523	6,671
NET INCOME (LOSS)			15,976	(4,515)
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
REVENUE			70,421	66,412
EXPENSES:
Depreciation and amortization			40,248	42,731
Cost of sales			235	51
Selling, general and administrative			9,306	9,437
Total operating expenses			49,789	52,219
INCOME (LOSS) FROM OPERATIONS			20,632	14,193
Interest expense, net			(8,464)	(9,936)
Foreign currency exchange losses			(4)	4
Gain on sale of marketable securities			230	2,467
Other income			482	27
Income (loss) before income taxes and equity in income of subsidiaries			12,876	6,755
Provision for income taxes			88	438
Equity in income of subsidiaries			9,735	354
NET INCOME (LOSS)			22,523	6,671
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
REVENUE			48,836	29,264
EXPENSES:
Depreciation and amortization			28,973	22,929
Cost of sales			13	4
Selling, general and administrative			5,999	5,646
Total operating expenses			34,985	28,579
INCOME (LOSS) FROM OPERATIONS			13,851	685
Interest expense, net			(634)	(342)
Foreign currency exchange losses			(11)	453
Gain on sale of marketable securities			0	0
Other income			0	135
Income (loss) before income taxes and equity in income of subsidiaries			13,206	931
Provision for income taxes			3,471	577
Equity in income of subsidiaries			0	0
NET INCOME (LOSS)			9,735	354
Consolidating Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
REVENUE			(682)	(635)
EXPENSES:
Depreciation and amortization			0	0
Cost of sales			0	0
Selling, general and administrative			(682)	(635)
Total operating expenses			(682)	(635)
INCOME (LOSS) FROM OPERATIONS			0	0
Interest expense, net			0	0
Foreign currency exchange losses			0	0
Gain on sale of marketable securities			0	0
Other income			0	0
Income (loss) before income taxes and equity in income of subsidiaries			0	0
Provision for income taxes			0	0
Equity in income of subsidiaries			(32,258)	(7,025)
NET INCOME (LOSS)			$ (32,258)	$ (7,025)