Differentiation between Federal Statutory Tax Rate and Overall Effective Tax Rate (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Tax Rate Reconciliation [Line Items]
Statutory provision	21.00%	35.00%	21.00%	35.00%
State taxes, net of federal benefit	1.50%	1.10%	1.40%	1.90%
City taxes	0.20%	0.20%	0.20%	0.10%
Foreign effective tax rates different from US statutory rate	(0.40%)	(9.60%)	0.50%	(10.60%)
Prior Year related state tax payment				0.90%
Valuation Reserve Adjustment				(2.90%)
Tax (Reserve) /Charge	0.40%		0.40%
Permanent difference federal tax (BEAT)	0.70%		1.50%
Permanent difference State/City tax (GILTI)	3.10%		1.50%
Effective Income Tax Rate	26.50%	26.70%	26.50%	24.40%