Fair Value Measurements (Details) (Level 1, USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Level 1
Investment in Global	$ 13,909	[1]	$ 23,607	[1]

[1] Global's ordinary shares are publicly traded on the Alternative Investment Market ("AIM"), a market operated by the London Stock Exchange, with quoted prices in active markets. Accordingly, the fair value measurements of these securities have been classified as Level 1.