Fair Value (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value of Assets and Liabilities Measured on a Recurring Basis

Valuation of our financial instruments by pricing observability levels as of December 31, 2018 and 2017 was as follows (in thousands):

	Level 1		Level 2		Level 3		NAV Expedient(1)		Other		Total
December 31, 2018:
Money markets	$	102,888	$	—	$	—	$	—	$	—	$	102,888
Securities segregated (U.S. Treasury Bills)	—		1,169,554		—		—		—		1,169,554
Derivatives	1,594		15,485		—		—		—		17,079
Investments
U.S. Treasury Bills	—		392,424		—		—		—		392,424
Equity securities	209,414		8,372		142		315		—		218,243
Long exchange-traded options	2,568		—		—		—		—		2,568
Limited partnership hedge       funds(2)	—		—		—		—		80,699		80,699
Time deposits(3)	—		—		—		—		8,783		8,783
Other investments	4,269		—		—		—		7,358		11,627
Total investments	216,251		400,796		142		315		96,840		714,344
Total assets measured at fair value	$	320,733	$	1,585,835	$	142	$	315	$	96,840	$	2,003,865
Securities sold not yet purchased
Short equities – corporate	$	4,841	$	—	$	—	$	—	$	—	$	4,841
Short exchange-traded options	3,782		—		—		—		—		3,782
Derivatives	2,534		12,288		—		—		—		14,822
Contingent payment arrangements	—		—		7,336		—		—		7,336
Total liabilities measured at fair value	$	11,157	$	12,288	$	7,336	$	—	$	—	$	30,781

	Level 1		Level 2		Level 3		NAV Expedient(1)		Other		Total
December 31, 2017:
Money markets	$	62,071	$	—	$	—	$	—	$	—	$	62,071
Securities segregated (U.S. Treasury Bills)	—		816,350		—		—		—		816,350
Derivatives	948		10,671		—		—		—		11,619
Investments
U.S. Treasury Bills	—		52,609		—		—		—		52,609
Equity securities	273,674		19,699		117		94		—		293,584
Long exchange-traded options	4,981		—		—		—		—		4,981
Limited partnership hedge       funds(2)	—		—		—		—		37,199		37,199
Private equity	—		—		954		37,232		—		38,186
Time deposits(3)	—		—		—		—		5,138		5,138
Other investments	—		—		—		—		11,892		11,892
Total investments	278,655		72,308		1,071		37,326		54,229		443,589
Total assets measured at fair value	$	341,674	$	899,329	$	1,071	$	37,326	$	54,229	$	1,333,629
Securities sold not yet purchased
Short equities – corporate	$	16,376	$	—	$	—	$	—	$	—	$	16,376
Short exchange-traded options	13,585		—		—		—		—		13,585
Derivatives	2,540		11,783		—		—		—		14,323
Contingent payment arrangements	—		—		10,855		—		—		10,855
Total liabilities measured at fair value	$	32,501	$	11,783	$	10,855	$	—	$	—	$	55,139

⁽¹⁾ Investments measured at fair value using NAV (or its equivalent) as a practical expedient.

⁽²⁾ Investments in equity method investees that are not measured at fair value in accordance with GAAP.

⁽³⁾ Investments carried at amortized cost that are not measured at fair value in accordance with GAAP.

Fair Value Measurement Level 3 Reconciliation

The change in carrying value associated with Level 3 financial instruments carried at fair value, classified as private equity and equity securities, is as follows:

	December 31, 2018			December 31, 2017
	(in thousands)
Balance as of beginning of period	$	1,071		$	5,023
Purchases	—			—
Sales	—			—
Realized gains, net	—			—
Unrealized (losses) gains, net	(929		)	(3,952		)
Balance as of end of period	$	142		$	1,071

Schedule of Contingent Payment Arrangements Level 3 Financial Instruments

The change in carrying value associated with Level 3 financial instruments carried at fair value, classified as contingent payment arrangements, is as follows:

	December 31, 2018			December 31, 2017
	(in thousands)
Balance as of beginning of period	$	10,855		$	17,589
Addition	—			—
Accretion	210			460
Changes in estimates	(2,429		)	(193		)
Payments	(1,300		)	(7,001		)
Balance as of end of period	$	7,336		$	10,855