CONSOLIDATED STATEMENTS OF EQUITY - USD ($) shares in Thousands, $ in Thousands	Parent	Common Stock	Capital in Excess of Par Value	Cumulative Net Income	Accumulated Other Comprehensive Income (Loss)	Cumulative Distributions	Non-controlling Interests	Total
Balance at beginning of period at Dec. 31, 2015	$ 659,202	$ 375	$ 758,676	$ 928,328	$ 47	$ (1,028,224)		$ 659,202
Balance (in shares) at Dec. 31, 2015		37,548
Equity activity
Reclassification adjustment	(47)				$ (47)			(47)
Issuance of common stock	78,136	$ 16	78,120					78,136
Issuance of common stock (in shares)		1,643
Issuance of restricted stock	(41)	$ 1	(42)					(41)
Issuance of restricted stock (in shares)		73
Net income	85,115			85,115				85,115
Vesting of restricted stock	4,265		4,265					4,265
Vested stock options	15		15					15
Stock option exercises	159		159					159
Stock option exercises (in shares)		7
Common stock cash distributions	(84,568)					(84,568)		(84,568)
Other	(2,188)		(2,188)					(2,188)
Other (in shares)		(50)
Balance at end of period at Dec. 31, 2016	740,048	$ 392	839,005	1,013,443		(1,112,792)		740,048
Balance (in shares) at Dec. 31, 2016		39,221
Equity activity
Issuance of common stock	14,529	$ 3	14,526					14,529
Issuance of common stock (in shares)		313
Issuance of restricted stock	(20)	$ 1	(21)					(20)
Issuance of restricted stock (in shares)		85
Net income	87,340			87,340				87,340
Vesting of restricted stock	5,247		5,247					5,247
Vested stock options	2		2					2
Stock option exercises	202		202					202
Stock option exercises (in shares)		8
Non-controlling interests contribution							$ 3,488	3,488
Common stock cash distributions	(90,219)					(90,219)		(90,219)
Other	(1,969)		(1,969)					(1,969)
Other (in shares)		(57)
Balance at end of period at Dec. 31, 2017	755,160	$ 396	856,992	1,100,783		(1,203,011)	3,488	758,648
Balance (in shares) at Dec. 31, 2017		39,570
Equity activity
Issuance of common stock	929		929					929
Issuance of common stock (in shares)		22
Issuance of restricted stock	(8)	$ 1	(9)					(8)
Issuance of restricted stock (in shares)		91
Net income	154,981			154,981			95	155,076
Vesting of restricted stock	5,870		5,870					5,870
Stock option exercises	123		123					123
Stock option exercises (in shares)		5
Non-controlling interests contribution							3,963	3,963
Non-controlling interest distributions							(65)	(65)
Common stock cash distributions	(90,372)					(90,372)		(90,372)
Other	(1,193)		(1,193)					(1,193)
Other (in shares)		(31)
Balance at end of period at Dec. 31, 2018	$ 825,490	$ 397	$ 862,712	$ 1,255,764		$ (1,293,383)	$ 7,481	$ 832,971
Balance (in shares) at Dec. 31, 2018		39,657