Investment in AB (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Change in Equity Method Investment
Beginning balance	$ 1,605,941	$ 1,554,203
Equity in net income attributable to AB Unitholders	416,326	308,404	$ 266,292
Changes in accumulated other comprehensive income	1,193	6,730	(1,167)
Cash distributions received from AB	(385,236)	(298,919)	(249,463)
Additional investments with proceeds from exercises of compensatory options to buy AB Holding Units	3,402	147	11,511
Capital contributions from AB	(2,346)	(867)
AB Holding Units retired	(143,460)	(78,388)	(110,752)
AB Holding Units issued to fund long-term incentive compensation plans	151,082	107,366	146,488
Change in AB Holding Units held by AB for long-term incentive compensation plans	(23,138)	7,265
Ending balance	$ 1,623,764	$ 1,605,941	$ 1,554,203