Financial Instruments - Additional Information (Details) - USD ($) shares in Millions		3 Months Ended
	Jul. 05, 2019	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Schedule Of Investments [Line Items]
Cash, cash equivalents and short -term investments		$ 142,500,000		$ 121,500,000
Gross realized gains and losses on sales of marketable securities		0	$ 0
Unrealized loss net of tax on marketable debt securities		300,000		100,000
Impairment charges related to marketable debt securities			0
Provision for credit loss expense related available for sale debt securities		0
Marketable equity securities, unrealized losses		$ (733,000)	(410,000)
Onkyo Corporation
Schedule Of Investments [Line Items]
Number of common shares purchased		7.0
Ownership interest, percentage		6.30%
Number of investment shares sold	2.8
Equity securities, realized gains or losses on sales	$ 900,000	$ 0	0
Marketable equity securities, unrealized losses		(700,000)	$ (400,000)
Cumulative unrealized losses on the investment		3,000,000.0
Operating Accounts
Schedule Of Investments [Line Items]
Cash, cash equivalents and short -term investments		$ 73,600,000		$ 72,000,000.0