Financial Highlights - Schedule of condensed financial information for an accumulation unit of the account (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022
Per Accumulation Unit Data:
Rental income (in dollars per share)	$ 13.271	$ 23.751	$ 22.672	$ 21.145
Real estate property level expenses and taxes (in dollars per share)	6.375	11.042	10.683	10.027
Real estate income, net (in dollars per share)	6.896	12.709	11.989	11.118
Other income (in dollars per share)	3.751	6.559	5.474	4.980
Total income (in dollars per share)	10.647	19.268	17.463	16.098
Expense charges (in dollars per share)	3.004	5.121	4.035	3.603
Investment income, net (in dollars per share)	7.643	14.147	13.428	12.495
Net realized and unrealized (loss) gain on investments and debt (in dollars per share)	(46.033)	28.011	64.615	(16.195)
Net increase (decrease) in Accumulation Unit Value (in dollars per share)	(38.390)	42.158	78.043	(3.700)
Accumulation Unit Value:
Beginning of period (in dollars per share)	556.923	514.765	436.722	440.422
End of period (in dollars per share)	$ 518.533	$ 556.923	$ 514.765	$ 436.722
Total return	(6.89%)	8.19%	17.87%	(0.84%)
Ratios to Average net assets:
Expenses	1.10%	0.89%	0.84%	0.81%
Investment income, net	2.80%	2.45%	2.82%	2.85%
Portfolio turnover rate:
Real estate properties	0.70%	5.60%	7.60%	7.10%
Marketable securities	9.00%	4.70%	0.00%	113.40%
Accumulation Units outstanding at end of period (millions) (in shares)	49.0	52.1	53.4	52.0
Net assets end of period (millions)	$ 25,998.1	$ 29,658.1	$ 28,072.0	$ 23,243.9	$ 28,050.3	$ 31,448.8	$ 29,771.0