Segment Reporting and Geographic Information (External Revenue and Long-Lived Assets by Geographic Region) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 38,175	$ 37,626	$ 77,080	$ 71,041
Long-Lived Assets	5,038		5,038		3,735
Americas
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	14,531	13,035	28,281	25,883
Long-Lived Assets	3,474		3,474		2,099
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	21,869	23,277	45,290	42,906
Long-Lived Assets	1,524		1,524		1,590
Asia Pacific
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	1,775	1,314	3,509	2,252
Long-Lived Assets	$ 40		$ 40		$ 46