Cash and Cash Equivalents - Geographic Information (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2012
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 87,642	$ 76,174	$ 49,745	$ 44,593
United States [Member]
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	29,412	30,082
Asia [Member]
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	45,789	34,627
Europe [Member]
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	9,186	7,161
South America [Member]
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 3,255	$ 4,304