Operating Leases - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property Subject To Or Available For Operating Lease [Line Items]
Non-cancelable operating leases, date of expiration	2022
Rent expense	$ 6,556	$ 7,634	$ 7,490
Maryland | Annapolis, first facility
Property Subject To Or Available For Operating Lease [Line Items]
Lease expiration date	2019-07
Maryland | Annapolis, second facility
Property Subject To Or Available For Operating Lease [Line Items]
Lease expiration date	2017-08
Seattle, Washington
Property Subject To Or Available For Operating Lease [Line Items]
Lease expiration date	2017-10
Tampa, Florida
Property Subject To Or Available For Operating Lease [Line Items]
Lease expiration date	2022-12
Aliso Viejo, California
Property Subject To Or Available For Operating Lease [Line Items]
Lease expiration date	2017-12
Atlanta Georgia
Property Subject To Or Available For Operating Lease [Line Items]
Lease expiration date	2020-08
Richardson Texas
Property Subject To Or Available For Operating Lease [Line Items]
Lease expiration date	2015-04
North Wollongong Australia
Property Subject To Or Available For Operating Lease [Line Items]
Lease expiration date	2017-04
Torrance, California
Property Subject To Or Available For Operating Lease [Line Items]
Lease expiration date	2018-01
Danville, Vermont
Property Subject To Or Available For Operating Lease [Line Items]
Lease expiration date	2017-06
Greenwood Village, Colorado
Property Subject To Or Available For Operating Lease [Line Items]
Lease expiration date	2020-05