Income Taxes (Statutory Tax Rate and Effective Tax Rate) (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Examination [Line Items]
Statutory federal tax	$ 28,196	$ 19,396	$ 14,815
State income taxes, net of federal benefit	1,470	864	769
Share-based compensation	(415)	(6,424)	(1,852)
Other permanent differences	1,218	1,004	615
Research and development and jobs credits	(370)	(579)	(85)
Valuation allowance	1,342
Other	(236)	182	323
Provision for income taxes	$ 31,406	$ 14,447	$ 14,759
Effective tax rate, Statutory federal tax	21.00%	21.00%	21.00%
Effective tax rate, State income taxes, net of federal benefit	1.10%	0.90%	1.10%
Effective tax rate, Share-based compensation	(0.30%)	(7.00%)	(2.60%)
Effective tax rate, Other permanent differences	0.90%	1.10%	0.80%
Effective tax rate, Research and development and jobs credits	(0.30%)	(0.60%)	(0.10%)
Effective tax rate, Valuation allowance	1.00%	0.00%	0.00%
Effective tax rate, Other	(0.20%)	0.20%	0.40%
Effective tax rate, Total	23.40%	15.60%	20.90%
Inland Revenue, Hong Kong [Member]
Income Tax Examination [Line Items]
Foreign taxes	$ 94	$ 1	$ 81
Effective tax rate, Foreign taxes	0.10%	0.00%	0.10%
Inland Revenue, Singapore (IRAS) [Member]
Income Tax Examination [Line Items]
Foreign taxes	$ 107	$ 3	$ 93
Effective tax rate, Foreign taxes	0.10%	0.00%	0.20%

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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