Consolidated Statements of Changes In Equity - USD ($) $ in Thousands	Total	Common Stock	Paid-in Capital	Paid-in Capital Preferred Stock	Redeemable Perpetual Preferred Stock	Redeemable Perpetual Preferred Stock Preferred Stock	Distributions in Excess of Accumulated Earnings	Accumulated Other Comprehensive Income (Loss)	Non- Controlling Interests – Common OP Units
Balance at Dec. 31, 2016	$ 1,081,847	$ 1,708	$ 1,102,194		$ 136,144		$ (231,276)	$ (227)	$ 73,304
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exchange of Common OP Units for Common Stock		26	16,423						(16,449)
Issuance of Common Stock through exercise of options	4,850	4	4,846
Issuance of Common Stock through employee stock purchase plan	2,061		2,061
Issuance of stock	120,698	28	120,670	$ 757		$ (757)
Compensation expenses related to restricted stock and stock options	9,352		9,352
Repurchase of Common Stock or Common OP Units	(3,087)		(3,087)
Adjustment for Common OP Unitholders in the Operating Partnership			(10,043)						10,043
Adjustment for fair market value of swap	1,169							1,169
Consolidated net income	210,377				7,685		189,904		12,788
Distributions	(188,964)				(6,928)		(170,608)		(11,428)
Series C Preferred stock redemption	(136,144)				(136,144)
Other	(2,117)		(1,947)						(170)
Balance at Dec. 31, 2017	1,100,042	1,766	1,241,226		0		(211,980)	942	68,088
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exchange of Common OP Units for Common Stock		2	1,023						(1,025)
Issuance of Common Stock through exercise of options	3,823	4	3,819
Issuance of Common Stock through employee stock purchase plan	2,043		2,043
Issuance of stock	78,755	20	78,735
Compensation expenses related to restricted stock and stock options	9,995		9,995
Repurchase of Common Stock or Common OP Units	(3,011)		(3,011)
Adjustment for Common OP Unitholders in the Operating Partnership			(3,684)						3,684
Adjustment for fair market value of swap	1,357							1,357
Consolidated net income	226,386				16		212,596		13,774
Distributions	(209,209)				(16)		(196,464)		(12,729)
Other	(1,651)
Balance at Dec. 31, 2018	1,193,344	1,792	1,328,495		0		(211,034)	2,299	71,792
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exchange of Common OP Units for Common Stock		10	6,539						(6,549)
Issuance of Common Stock through exercise of options	53		53
Issuance of Common Stock through employee stock purchase plan	2,429		2,429
Issuance of stock	59,319	10	59,309
Compensation expenses related to restricted stock and stock options	10,481		10,481
Repurchase of Common Stock or Common OP Units	(53)		(53)
Adjustment for Common OP Unitholders in the Operating Partnership			(3,210)						3,210
Adjustment for fair market value of swap	(2,679)							(2,679)
Consolidated net income	295,922				16		279,123		16,783
Distributions	(235,581)				(16)		(222,407)		(13,158)
Other	(1,347)		(1,347)
Balance at Dec. 31, 2019	$ 1,321,888	$ 1,812	$ 1,402,696		$ 0		$ (154,318)	$ (380)	$ 72,078