CONSOLIDATED SUPPLEMENTARY FINANCIAL DATA (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenue:
Total revenue	$ 73,422	$ 73,294	$ 57,919	$ 66,866	$ 57,443	$ 57,530	$ 56,215	$ 62,863	$ 271,501	$ 234,051	$ 312,363
Operating costs and expenses:
Total operating costs and expenses	67,208	64,229	52,175	65,425	61,470	104,630	77,964	80,421	249,037	324,485	313,899
Operating income (loss)	6,214	9,065	5,744	1,441	(4,027)	(47,100)	(21,749)	(17,558)	22,464	(90,434)	(1,536)
Net loss	$ (9,777)	$ (5,725)	$ (7,844)	$ (10,402)	$ (16,132)	$ (58,098)	$ (32,216)	$ (27,890)	$ (33,748)	$ (134,336)	$ (43,053)
Net loss per share:
Net income (loss) per share - basic (in dollars per share)	$ (0.09)	$ (0.05)	$ (0.07)	$ (0.09)	$ (0.14)	$ (0.52)	$ (0.29)	$ (0.25)	$ (0.30)	$ (1.21)	$ (0.39)
Net income (loss) per share - diluted (in dollars per share)	$ (0.09)	$ (0.05)	$ (0.07)	$ (0.09)	$ (0.14)	$ (0.52)	$ (0.29)	$ (0.25)	$ (0.30)	$ (1.21)	$ (0.39)
Shares used in per share calculations:
Basic (in shares)	113,217	112,640	112,183	111,599	111,332	110,826	110,553	110,358	112,415	110,769	110,041
Diluted (in shares)	113,217	112,640	112,183	111,599	111,332	110,826	110,553	110,358	112,415	110,769	110,041