Variable Interest Entities VIEs (Details) (USD $)	3 Months Ended
	Mar. 31, 2011	Mar. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Assets
Cash and cash equivalents	$ 434,561,000	$ 511,078,000	$ 424,155,000	$ 276,915,000
Other current assets		11,149,000	10,096,000
Licenses	1,452,401,000	1,481,865,000	1,470,769,000	1,452,101,000
Property, plant and equipment, net		2,847,426,000	2,790,302,000
Other assets and deferred charges		65,094,000	59,290,000
Liabilities
Customer deposits and deferred revenues		190,866,000	181,355,000
Current liabilities		646,293,000	722,280,000
Capital contributions and advances	6,800,000
Variable Interest Entities (VIE's)
Assets
Cash and cash equivalents		4,115,000	12,086,000
Other current assets		173,000	47,000
Licenses		485,380,000	483,059,000
Property, plant and equipment, net		12,728,000	9,450,000
Other assets and deferred charges		70,000	153,000
Total assets		502,466,000	504,795,000
Liabilities
Current liabilities		227,000	957,000
Deferred liabilities and credits		1,566,000
Total liabilities		$ 1,793,000	$ 957,000