Summary of Significant Accounting Policies (Details) ft² in Millions, $ in Billions	Jun. 30, 2021 USD ($) ft² building property state
Business Overview:
Gross investment amount, total | $	$ 4.7
Number of real estate properties | property	227
Number of states that the company owns real estate in, whole units | state	24
Square footage of owned real estate properties	16.3
Approximate square feet for which Nationwide property management services provided by company	13.4
Joint venture ownership (percent)	50.00%
Number of buildings owned by joint venture with TIAA | building	9
Equity ownership for consolidation (percent)	100.00%