Fair Value Measurements (Unobservable Quantitative Input Ratios) (Details)	Dec. 31, 2021	Dec. 31, 2020
Discount rates
Unobservable Quantitative Input
Real estate, measurement input	0.070
Discount rates | Level 3 | Recurring | Loans Receivable
Unobservable Quantitative Input
Loans receivable, measurement input		0.065
Discount rates | Level 3 | Recurring | Weighted Average | Loans Receivable
Unobservable Quantitative Input
Loans receivable, measurement input	0.065	0.065
Discount rates | Level 3 | Recurring | Real estate fund investments | Minimum
Unobservable Quantitative Input
Real estate, measurement input	0.120	0.076
Discount rates | Level 3 | Recurring | Real estate fund investments | Maximum
Unobservable Quantitative Input
Real estate, measurement input	0.150	0.150
Discount rates | Level 3 | Recurring | Real estate fund investments | Weighted Average
Unobservable Quantitative Input
Real estate, measurement input	0.132	0.127
Terminal capitalization rates | Level 3 | Recurring | Loans Receivable
Unobservable Quantitative Input
Loans receivable, measurement input	0.050	0.050
Terminal capitalization rates | Level 3 | Recurring | Weighted Average | Loans Receivable
Unobservable Quantitative Input
Loans receivable, measurement input	0.050	0.050
Terminal capitalization rates | Level 3 | Recurring | Real estate fund investments | Minimum
Unobservable Quantitative Input
Real estate, measurement input	0.055	0.055
Terminal capitalization rates | Level 3 | Recurring | Real estate fund investments | Maximum
Unobservable Quantitative Input
Real estate, measurement input	0.088	0.103
Terminal capitalization rates | Level 3 | Recurring | Real estate fund investments | Weighted Average
Unobservable Quantitative Input
Real estate, measurement input	0.074	0.079