Consolidated Company-Sponsored Investment Funds - Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
VIEs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	$ 1,951	$ 3,224
Derivatives	4,349	6,893
VOEs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets		464
Derivatives		664
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	16,592	21,741
Derivatives	16,914	30,537
Total liabilities measured at fair value	66,807	76,078
Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	133,644	162,243
Derivative Assets	497	118
Total assets measured at fair value	292,985	293,036
Derivatives	758	1,834
Total liabilities measured at fair value	13,467	19,625
Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	18,450	17,565
Derivative Assets	16,095	21,623
Total assets measured at fair value	1,107,473	1,792,094
Derivatives	16,156	28,703
Total liabilities measured at fair value	16,156	28,703
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	126	125
Derivative Assets	0	0
Total assets measured at fair value	126	125
Derivatives	0	0
Total liabilities measured at fair value	37,184	27,750
Recurring | Company-sponsored investment funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	168,891	306,270
Total liabilities measured at fair value	4,349	7,557
Recurring | Company-sponsored investment funds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	53,268	74,351
Total liabilities measured at fair value	2,927	1,649
Recurring | Company-sponsored investment funds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	115,413	231,300
Total liabilities measured at fair value	1,422	5,908
Recurring | Company-sponsored investment funds | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	210	619
Total liabilities measured at fair value	0	0
Recurring | VIEs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	166,940	242,541
Derivative Assets	1,951	3,224
Derivatives	4,349	6,893
Recurring | VIEs | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	53,028	73,909
Derivative Assets	240	442
Derivatives	2,927	1,649
Recurring | VIEs | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	113,702	168,114
Derivative Assets	1,711	2,782
Derivatives	1,422	5,244
Recurring | VIEs | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	210	518
Derivative Assets	0	0
Derivatives	$ 0	0
Recurring | VOEs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments		60,041
Derivative Assets		464
Derivatives		664
Recurring | VOEs | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments		0
Derivative Assets		0
Derivatives		0
Recurring | VOEs | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments		59,940
Derivative Assets		464
Derivatives		664
Recurring | VOEs | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments		101
Derivative Assets		0
Derivatives		$ 0