Summary of Operations and Significant Accounting Policies (Revenues Attributable to Domestic and Foreign Operations) (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
Segment Reporting Information [Line Items]
Revenue	$ 43,229	$ 38,505	$ 85,725	$ 75,264
United States [Member]
Segment Reporting Information [Line Items]
Revenue	30,433	29,225	60,518	57,380
United Kingdom [Member]
Segment Reporting Information [Line Items]
Revenue	6,963	5,245	13,947	10,121
Other Countries [Member]
Segment Reporting Information [Line Items]
Revenue	$ 5,833	$ 4,035	$ 11,260	$ 7,763

Aggregate revenue recognized during the period (derived from goods sold, services rendered, insurance premiums, or other activities that constitute an entity's earning process). For financial services companies, also includes investment and interest income, and sales and trading gains.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1)

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

Name:	us-gaap_Revenues
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration