Income Taxes - Earliest Tax Years Subject to Examination by Major Jurisdiction (Detail)	9 Months Ended
	Sep. 30, 2020
U.S. Federal [Member]
Income Tax Examination [Line Items]
Open tax years by major tax jurisdiction	2011
State and Local Jurisdiction [Member] | New York State Division of Taxation and Finance [Member]
Income Tax Examination [Line Items]
Open tax years by major tax jurisdiction	2011
State and Local Jurisdiction [Member] | New York City Division Of Taxation And Finance [Member]
Income Tax Examination [Line Items]
Open tax years by major tax jurisdiction	2015
United Kingdom [Member] | Foreign Tax Authority [Member]
Income Tax Examination [Line Items]
Open tax years by major tax jurisdiction	2017
Japan [Member] | Foreign Tax Authority [Member]
Income Tax Examination [Line Items]
Open tax years by major tax jurisdiction	2015
Hong Kong [Member] | Foreign Tax Authority [Member]
Income Tax Examination [Line Items]
Open tax years by major tax jurisdiction	2014