Segment Reporting - Information on Long-Lived Assets and Net Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Property and equipment, net	$ 93,672	$ 84,577
U.S.
Segment Reporting Information [Line Items]
Property and equipment, net	63,563	59,611
Net assets	925,288	867,321
United Kingdom
Segment Reporting Information [Line Items]
Property and equipment, net	16,423	14,023
Net assets	196,087	160,894
All other foreign countries
Segment Reporting Information [Line Items]
Property and equipment, net	13,686	10,943
Net assets	$ 367,767	$ 320,610