Related-Party Transactions - Summary of Related-Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Related party assets
Cash and cash equivalents	$ 31,622		$ 31,622		$ 22,744
Investments (deferred compensation plan investments, fair value)	28,661		28,661		22,571
Related party revenue
Total revenue	221,904	$ 181,886	434,853	$ 386,307
Investment Management Fees
Related party revenue
Total revenue	168,033	130,032	328,317	276,913
Fund Administration and Distribution Fees
Related party revenue
Total revenue	53,871	51,854	106,536	109,394
VCH
Related party assets
Cash and cash equivalents	10,089		10,089		10,088
Receivables (investment management fees)	51,717		51,717		46,958
Receivables (fund administration and distribution fees)	16,857		16,857		16,971
Investments (investments in proprietary funds, fair value)	905		905		922
Investments (deferred compensation plan investments, fair value)	27,029		27,029		22,062
Total	106,597		106,597		97,001
Related party liabilities
Accounts payable and accrued expenses (fund reimbursements)	6,837		6,837		$ 5,978
Related party revenue
Total revenue	195,343	160,820	381,302	342,670
Related party expense
General and administrative	133		263
Total	133		263
Related party other income (expense)
Interest income and other income (expense)	1,908	2,702	4,583	(2,096)
VCH | Investment Management Fees
Related party revenue
Total revenue	141,472	108,966	274,766	233,276
VCH | Fund Administration and Distribution Fees
Related party revenue
Total revenue	$ 53,871	$ 51,854	$ 106,536	$ 109,394