Common Stock Capitalization (Summary of Common Stock Outstanding) (Details) - shares	3 Months Ended			6 Months Ended		13 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)	29,745,776	29,796,601	30,392,041	29,796,601	31,335,938
Shares repurchased	0		(242,161)	(50,825)	(1,186,058)	(411,915)
Director OP LTIP Units exercised	0		0	0	0
Ending balance (in shares)	29,745,776	29,745,776	30,149,880	29,745,776	30,149,880	29,745,776