Significant Accounting Policies - Investments in Unconsolidated Joint Ventures/Deferred Lease Costs/Revenue Recognition/Income Taxes (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Deferred Lease Costs [Abstract]
Portion of compensation capitalized	$ 6.2	$ 5.4	$ 6.3
Estimated average lease term (in years)	7 years
Days past due for income recognition on debt and preferred equity investments to be suspended	90 days
Income taxes
Federal, state and local tax provision	$ 2.8	$ 1.2	$ 1.5
Dividends per share paid (in dollars per share)	$ 8.09	$ 5.54	$ 3.40
Ordinary Income Dividend
Income taxes
Dividends per share paid (in dollars per share)	0.50	1.84	2.59
Capital Gains Dividend
Income taxes
Dividends per share paid (in dollars per share)	$ 5.92	$ 3.06	$ 0.81