Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Current assets:
Accounts receivable, allowance	$ 28	$ 27
Stockholders' equity
Common Stock, par value	$ 0.01	$ 0.01
Common Stock, shares authorized	1,500,000,000	1,500,000,000
Common Stock, shares issued	232,324,000	231,023,000
Common Stock, shares outstanding	225,824,000	224,523,000
Treasury shares	6,500,000	6,500,000
Series A-1 Preferred Stock [Member]
Stockholders' equity
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	2,000,000	2,000,000
Preferred stock, shares issued	991,000	953,000
Preferred stock, shares outstanding	991,000	953,000
Preferred stock, liquidation preference	991
Series B Preferred Stock [Member]
Stockholders' equity
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	14,000,000	14,000,000
Preferred stock, shares issued	10,564,000	10,058,000
Preferred stock, shares outstanding	10,564,000	10,058,000
Preferred stock, liquidation preference	15,846
Series C Preferred Stock [Member]
Stockholders' equity
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	4,100,000	4,100,000
Preferred stock, shares issued	4,385,000	4,175,000
Preferred stock, shares outstanding	4,385,000	4,175,000
Preferred stock, liquidation preference	6,577
Series D-1 Preferred Stock [Member]
Stockholders' equity
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	3,000,000	3,000,000
Preferred stock, shares issued	1,413,000	1,124,000
Preferred stock, shares outstanding	1,413,000	1,124,000
Preferred stock, liquidation preference	1,413
Series D-2 Preferred Stock [Member]
Stockholders' equity
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	8,000,000	8,000,000
Preferred stock, shares issued	4,400,000	3,302,000
Preferred stock, shares outstanding	4,400,000	3,302,000
Preferred stock, liquidation preference	$ 4,400