Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2020

Marketable Securities [Abstract]

Investments Available For Sale

Available For Sale and Equity Securities on the accompanying Consolidated Balance Sheets consist of: 

	At September 30, 2020
	Cost Amount		Gross Unrealized Gains		Gross Unrealized (Losses)		Fair Value
Available-for-sale debt securities	$	103,365	$	2,106	$	—	$	105,471
SEI-sponsored mutual funds	6,793		63		(277)		6,579
Equities and other mutual funds	3,605		909		—		4,514
	$	113,763	$	3,078	$	(277)	$	116,564

	At December 31, 2019
	Cost Amount		Gross Unrealized Gains		Gross Unrealized (Losses)		Fair Value
Available-for-sale debt securities	$	104,193	$	605	$	—	$	104,798
SEI-sponsored mutual funds	7,564		125		(39)		7,650
Equities and other mutual funds	3,637		832		—		4,469
	$	115,394	$	1,562	$	(39)	$	116,917