Operating Segment and Enterprise Wide Reporting - Schedule of Revenues by Geographic Destination, Based on Location Products and Services and as a Percentage of Total Revenues (Detail) - USD ($)
$ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2019

Sep. 30, 2019

Jun. 30, 2019

Mar. 31, 2019

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Revenues From External Customers And Long Lived Assets [Line Items]

Revenues by geographical area percentage

100.00%

Revenue

$ 124,269

$ 108,596

$ 128,183

$ 100,649

$ 98,583

$ 84,890

$ 96,353

$ 77,749

$ 461,697

$ 357,575

$ 337,673

United States [Member]

Revenues From External Customers And Long Lived Assets [Line Items]

Revenues by geographical area percentage

79.00%

77.00%

Revenue

$ 362,867

$ 274,151

$ 260,077

Europe (Excluding United Kingdom) [Member]

Revenues From External Customers And Long Lived Assets [Line Items]

Revenues by geographical area percentage

7.00%

8.00%

9.00%

Revenue

$ 32,585

$ 29,741

$ 28,525

United Kingdom [Member]

Revenues From External Customers And Long Lived Assets [Line Items]

Revenues by geographical area percentage

4.00%

Revenue

$ 21,316

$ 15,273

$ 13,651

Canada [Member]

Revenues From External Customers And Long Lived Assets [Line Items]

Revenues by geographical area percentage

4.00%

Revenue

$ 17,246

$ 15,569

$ 14,523

Asia Pacific [Member]

Revenues From External Customers And Long Lived Assets [Line Items]

Revenues by geographical area percentage

5.00%

4.00%

Revenue

$ 22,842

$ 17,839

$ 15,952

Other [Member]

Revenues From External Customers And Long Lived Assets [Line Items]

Revenues by geographical area percentage

1.00%

2.00%

Revenue

$ 4,841

$ 5,002

$ 4,945