Operating Segment and Enterprise Wide Reporting - Schedule of Revenues by Geographic Destination and as a Percentage of Total Revenues (Detail) - USD ($)
$ in Thousands |
3 Months Ended |
12 Months Ended |
Dec. 31, 2016 |
Sep. 30, 2016 |
Jun. 30, 2016 |
Mar. 31, 2016 |
Dec. 31, 2015 |
Sep. 30, 2015 |
Jun. 30, 2015 |
Mar. 31, 2015 |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
| Revenues From External Customers And Long Lived Assets [Line Items] |
|
|
|
|
|
|
|
|
|
|
|
| Revenue |
$ 83,446
|
$ 77,427
|
$ 87,821
|
$ 77,401
|
$ 80,975
|
$ 74,753
|
$ 82,811
|
$ 75,187
|
$ 326,095
|
$ 313,726
|
$ 312,062
|
| Revenues by geographical area percentage |
|
|
|
|
|
|
|
|
100.00%
|
100.00%
|
100.00%
|
| United States [Member] |
|
|
|
|
|
|
|
|
|
|
|
| Revenues From External Customers And Long Lived Assets [Line Items] |
|
|
|
|
|
|
|
|
|
|
|
| Revenue |
|
|
|
|
|
|
|
|
$ 252,222
|
$ 241,025
|
$ 232,440
|
| Revenues by geographical area percentage |
|
|
|
|
|
|
|
|
77.00%
|
77.00%
|
74.00%
|
| Europe (Excluding United Kingdom) [Member] |
|
|
|
|
|
|
|
|
|
|
|
| Revenues From External Customers And Long Lived Assets [Line Items] |
|
|
|
|
|
|
|
|
|
|
|
| Revenue |
|
|
|
|
|
|
|
|
$ 27,061
|
$ 24,607
|
$ 30,257
|
| Revenues by geographical area percentage |
|
|
|
|
|
|
|
|
8.00%
|
8.00%
|
10.00%
|
| United Kingdom [Member] |
|
|
|
|
|
|
|
|
|
|
|
| Revenues From External Customers And Long Lived Assets [Line Items] |
|
|
|
|
|
|
|
|
|
|
|
| Revenue |
|
|
|
|
|
|
|
|
$ 14,808
|
$ 16,815
|
$ 16,804
|
| Revenues by geographical area percentage |
|
|
|
|
|
|
|
|
5.00%
|
5.00%
|
5.00%
|
| Canada [Member] |
|
|
|
|
|
|
|
|
|
|
|
| Revenues From External Customers And Long Lived Assets [Line Items] |
|
|
|
|
|
|
|
|
|
|
|
| Revenue |
|
|
|
|
|
|
|
|
$ 13,806
|
$ 14,424
|
$ 17,089
|
| Revenues by geographical area percentage |
|
|
|
|
|
|
|
|
4.00%
|
5.00%
|
6.00%
|
| Other [Member] |
|
|
|
|
|
|
|
|
|
|
|
| Revenues From External Customers And Long Lived Assets [Line Items] |
|
|
|
|
|
|
|
|
|
|
|
| Revenue |
|
|
|
|
|
|
|
|
$ 18,198
|
$ 16,855
|
$ 15,472
|
| Revenues by geographical area percentage |
|
|
|
|
|
|
|
|
6.00%
|
5.00%
|
5.00%
|