Investment in AB (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Change in Equity Method Investment [Roll Forward]
Beginning balance	$ 2,077,540
Equity in net income attributable to AB Unitholders	86,281	$ 76,382
Changes in accumulated other comprehensive income	(4,159)	2,636
Cash distributions received from AB	(97,650)	$ (87,343)
Capital contributions (from) AB	(891)
AB Holding Units retired	(531)
AB Holding Units issued to fund long-term incentive compensation plans	16,014
Change in AB Holding Units held by AB for long-term incentive compensation plans	(7,853)
Ending balance	$ 2,068,751