Operating Segment and Enterprise Wide Reporting - Schedule of Net Long-lived Tangible Assets by Location (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Net long-lived tangible assets	$ 32,174	$ 39,868
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net long-lived tangible assets	28,558	35,167
United Kingdom [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net long-lived tangible assets	1,625	2,212
Europe (Excluding United Kingdom) [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net long-lived tangible assets	329	174
Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net long-lived tangible assets	$ 1,662	$ 2,315