Loans Receivable (Summary of Loan Activity) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Advances on loans receivable:
Net cash advances on loans receivable	$ 247,543	$ 119,699	$ 112,048
Receipts on loans receivable:
Net cash receipts on loans receivable	31,548	127,706	203,935
Seniors Housing Operating
Advances on loans receivable:
Investments in new loans	224,078	46,824	77,289
Draws on existing loans	23,465	72,875	34,759
Net cash advances on loans receivable	247,543	119,699	112,048
Receipts on loans receivable:
Loan payoffs	15,677	118,703	144,700
Principal payments on loans	15,871	9,003	59,235
Net cash receipts on loans receivable	31,548	127,706	203,935
Net cash advances (receipts) on loans receivable	$ 215,995	$ (8,007)	$ (91,887)