Investments (Tables)

12 Months Ended

Dec. 31, 2018

Investments, Debt and Equity Securities [Abstract]

Summary of Investments

Investments consist of:

	December 31,
	2018		2017
	(in thousands)
U.S. Treasury Bills	$	392,424	$	52,609
Equity securities:
Long-term incentive compensation-related	38,883		51,758
Seed capital	105,951		160,672
Other	73,409		81,154
Exchange-traded options	2,568		4,981
Investments in limited partnership hedge funds:
Long-term incentive compensation-related	13,546		14,276
Seed capital	67,153		22,923
Private equity (seed capital)	—		38,186
Time deposits	8,783		5,138
Other	11,627		11,892
Total investments	$	714,344	$	443,589

Summary of the Cost and Fair Value of Available-For-Sale and Trading Investments

The portion of unrealized gains (losses) related to equity securities, as defined by ASU 2016-01, held as of December 31, 2018 and 2017 were as follows:

	December 31,
	2018			2017
	(in thousands)
Net (loss) gain recognized during the period	$	(21,797	)	$	20,873
Less: net gains recognized during the period on equity securities sold during the period	1,515			24,594
Unrealized losses recognized during the period on equity securities held	$	(23,312	)	$	(3,721	)