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, 2020	$ 767,402	$ 392	$ 852,780	$ 1,388,775		$ (1,474,545)	$ 8,404	$ 775,806
Balance (in shares) at Dec. 31, 2020		39,242
Equity activity
Common stock cash distributions	(22,405)					(22,405)		(22,405)
Vesting of performance-based stock units, including the payment of distributions	(764)	$ 1	(1)			(764)		(764)
Vesting of performance-based stock units, including the payment of distributions (in shares)		109
Stock-based compensation expense	1,852		1,852					1,852
Net income	13,762			13,762			88	13,850
Non-controlling interest distributions							(88)	(88)
Cash paid for taxes in lieu of common shares	(3,470)		(3,470)					(3,470)
Cash paid for taxes in lieu of common shares (in shares)		(84)
Other	(10)	$ 1	(11)					(10)
Other (in shares)		95
Balance (in shares) at Mar. 31, 2021		39,362
Balance at end of period at Mar. 31, 2021	756,367	$ 394	851,150	1,402,537		(1,497,714)	8,404	764,771
Balance at beginning of period at Dec. 31, 2020	767,402	$ 392	852,780	1,388,775		(1,474,545)	8,404	775,806
Balance (in shares) at Dec. 31, 2020		39,242
Equity activity
Net income								32,180
Balance (in shares) at Jun. 30, 2021		39,374
Balance at end of period at Jun. 30, 2021	753,976	$ 394	852,959	1,420,776		(1,520,153)	8,404	762,380
Balance at beginning of period at Mar. 31, 2021	756,367	$ 394	851,150	1,402,537		(1,497,714)	8,404	764,771
Balance (in shares) at Mar. 31, 2021		39,362
Equity activity
Common stock cash distributions	(22,439)					(22,439)		(22,439)
Stock-based compensation expense	1,958		1,958					1,958
Net income	18,239			18,239			91	18,330
Non-controlling interest distributions							(91)	(91)
Cash paid for taxes in lieu of common shares	(103)		(103)					(103)
Cash paid for taxes in lieu of common shares (in shares)		(3)
Other	(46)		(46)					(46)
Other (in shares)		15
Balance (in shares) at Jun. 30, 2021		39,374
Balance at end of period at Jun. 30, 2021	753,976	$ 394	852,959	1,420,776		(1,520,153)	8,404	762,380
Equity activity
Common stock cash distributions	(22,443)					(22,443)		(22,443)
Stock-based compensation expense	1,975		1,975					1,975
Net income	11,022			11,022			92	11,114
Non-controlling interest distributions							(92)	(92)
Non-controlling interests contributions							9	9
Other	(13)		(13)					(13)
Balance (in shares) at Sep. 30, 2021		39,374
Balance at end of period at Sep. 30, 2021	744,517	$ 394	854,921	1,431,798		(1,542,596)	8,413	752,930
Equity activity
Common stock cash distributions	(22,443)					(22,443)		(22,443)
Stock-based compensation expense	1,975		1,975					1,975
Net income	12,838			12,838			92	12,930
Non-controlling interest distributions							(92)	(92)
Fair market valuation adjustment for interest rate swap	(172)				$ (172)			(172)
Other	(1)		(1)					(1)
Balance (in shares) at Dec. 31, 2021		39,374
Balance at end of period at Dec. 31, 2021	736,714	$ 394	856,895	1,444,636	(172)	(1,565,039)	8,413	745,127
Equity activity
Common stock cash distributions	(22,480)					(22,480)		(22,480)
Stock-based compensation expense	1,925		1,925					1,925
Net income	14,412			14,412			95	14,507
Non-controlling interest distributions							(95)	(95)
Cash paid for taxes in lieu of common shares	(1,255)		(1,255)					(1,255)
Cash paid for taxes in lieu of common shares (in shares)		(37)
Fair market valuation adjustment for interest rate swap	4,876				4,876			4,876
Other	(6)	$ 1	(7)					(6)
Other (in shares)		123
Balance (in shares) at Mar. 31, 2022		39,460
Balance at end of period at Mar. 31, 2022	734,186	$ 395	857,558	1,459,048	4,704	(1,587,519)	8,413	742,599
Balance at beginning of period at Dec. 31, 2021	736,714	$ 394	856,895	1,444,636	(172)	(1,565,039)	8,413	745,127
Balance (in shares) at Dec. 31, 2021		39,374
Equity activity
Net income								68,997
Balance (in shares) at Jun. 30, 2022		40,380
Balance at end of period at Jun. 30, 2022	802,974	$ 404	893,154	1,513,431	6,139	(1,610,154)	7,522	810,496
Balance at beginning of period at Mar. 31, 2022	734,186	$ 395	857,558	1,459,048	4,704	(1,587,519)	8,413	742,599
Balance (in shares) at Mar. 31, 2022		39,460
Equity activity
Issuance of common stock	33,693	$ 9	33,684					33,693
Issuance of common stock (in shares)		910
Common stock cash distributions	(22,635)					(22,635)		(22,635)
Stock-based compensation expense	2,012		2,012					2,012
Net income	54,383			54,383			107	54,490
Non-controlling interest distributions							(998)	(998)
Cash paid for taxes in lieu of common shares	(100)		(100)					(100)
Cash paid for taxes in lieu of common shares (in shares)		(2)
Fair market valuation adjustment for interest rate swap	1,435				1,435			1,435
Other (in shares)		12
Balance (in shares) at Jun. 30, 2022		40,380
Balance at end of period at Jun. 30, 2022	$ 802,974	$ 404	$ 893,154	$ 1,513,431	$ 6,139	$ (1,610,154)	$ 7,522	$ 810,496