Selected Quarterly Financial Data - Additional Information (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Quarterly Financial Information Disclosure [Abstract]
Non-cash goodwill impairment, per share			$ 0.66
Restructuring charges	$ 3,500		$ 4,811	[1]	$ 5,116	[1]	$ 0
Impairment charge		1,300	44,257		0		0
Gain on sales of cost-based investments		7,600	1,165		7,647		0
Other-than-temporary loss on cost-based investments		$ 2,700	$ 88		$ 2,724		$ 0

[1] As disclosed on the Company's consolidated statements of cash flows, total non-cash equity compensation expense was $3.9 million and $5.0 million in 2012 and 2011, respectively. Included in non-cash equity compensation expense in 2012 and 2011 were net charges to expense of approximately $0.1 million and reversals of expense of approximately $0.5 million, respectively, which were generated in connection with restructuring activities. Accordingly, these amounts are reflected as restructuring charges in the Company's 2012 and 2011 consolidated statements of operations. See Note 14, Restructuring charges for further information.