Operating Segment and Enterprise Wide Reporting - Schedule of Net Revenues by Geographic Destination and as a Percentage of Total Revenues (Detail) (USD $)
In Thousands, unless otherwise specified

3 Months Ended

12 Months Ended

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Revenues from External Customers and Long-Lived Assets [Line Items]

Revenue

$ 77,521

$ 69,815

$ 78,953

$ 71,361

$ 75,161

$ 68,773

$ 78,932

$ 70,165

$ 297,650

$ 293,031

$ 283,335

Revenues by geographical area percentage

100.00%

United States [Member]

Revenues from External Customers and Long-Lived Assets [Line Items]

Revenue

218,900

211,211

198,175

Revenues by geographical area percentage

74.00%

72.00%

70.00%

Europe (Excluding United Kingdom) [Member]

Revenues from External Customers and Long-Lived Assets [Line Items]

Revenue

30,956

33,146

37,205

Revenues by geographical area percentage

10.00%

11.00%

13.00%

United Kingdom [Member]

Revenues from External Customers and Long-Lived Assets [Line Items]

Revenue

16,293

16,555

17,870

Revenues by geographical area percentage

5.00%

6.00%

Canada [Member]

Revenues from External Customers and Long-Lived Assets [Line Items]

Revenue

16,995

16,742

16,056

Revenues by geographical area percentage

6.00%

Other [Member]

Revenues from External Customers and Long-Lived Assets [Line Items]

Revenue

$ 14,506

$ 15,377

$ 14,029

Revenues by geographical area percentage

5.00%