Summary of Significant Accounting Policies - Carrying Amount of Intangible Assets (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Indefinite-lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	$ 0	$ 8,731,000
Finite-Lived Intangible Assets, Accumulated Amortization	0	(8,630,000)
Finite-Lived Intangible Assets, Net	0	101,000
Internet Domain Names, Trade Names and Intellectual Property [Member]
Indefinite-lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	0	6,196,000
Finite-Lived Intangible Assets, Accumulated Amortization	0	(6,095,000)
Finite-Lived Intangible Assets, Net	0	101,000
Purchased Technology [Member]
Indefinite-lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	0	2,535,000
Finite-Lived Intangible Assets, Accumulated Amortization	0	(2,535,000)
Finite-Lived Intangible Assets, Net	$ 0	$ 0