CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY - USD ($)	Total	Common Stock [Member]	Additional Paid In Capital [Member]	Retained Earnings [Member]
Balances at Dec. 31, 2019	$ 395,507,000	$ 631,000	$ 414,998,000	$ (20,122,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Profit Loss	(91,199,000)	0	0	(91,199,000)
Cash dividend declared	15,670,000	0	15,670,000	0
Issuance of common stock pursuant to public offerings, net	19,447,000	31,000	19,416,000	0
Stock Issued During Period Value Share Based Compensation	59,000	0	59,000	0
Balances at Mar. 31, 2020	$ 308,144,000	662,000	418,803,000	(111,321,000)
Common Stock Shares Outstanding, Beginning Balance at Dec. 31, 2019	63,062,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period Shares New Issues	3,171,000
Stock Issued During Period Shares Share Based Compensation	4,000
Common Stock Shares Outstanding, Ending Balance at Mar. 31, 2020	66,237,000
Balances at Dec. 31, 2019	$ 395,507,000	631,000	414,998,000	(20,122,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Profit Loss	(14,351,000)
Balances at Sep. 30, 2020	$ 376,741,000	693,000	410,521,000	(34,473,000)
Common Stock Shares Outstanding, Beginning Balance at Dec. 31, 2019	63,062,000
Common Stock Shares Outstanding, Ending Balance at Sep. 30, 2020	69,296,000
Balances at Dec. 31, 2019	$ 395,507,000	631,000	414,998,000	(20,122,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock pursuant to public offerings, net	71,050,000
Balances at Dec. 31, 2020	$ 415,291,000	761,000	432,524,000	(17,994,000)
Common Stock Shares Outstanding, Beginning Balance at Dec. 31, 2019	63,062,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period Shares New Issues	13,019,240
Common Stock Shares Outstanding, Ending Balance at Dec. 31, 2020	76,073,317
Balances at Mar. 31, 2020	$ 308,144,000	662,000	418,803,000	(111,321,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Profit Loss	48,772,000	0	0	48,772,000
Cash dividend declared	10,935,000	0	10,935,000	0
Stock Issued During Period Value Share Based Compensation	55,000	0	55,000	0
Stock Repurchased and Retired During Period, Value	(68,000)	0	(68,000)	0
Balances at Jun. 30, 2020	$ 345,968,000	662,000	407,855,000	(62,549,000)
Common Stock Shares Outstanding, Beginning Balance at Mar. 31, 2020	66,237,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period Shares Share Based Compensation	4,000
Stock Repurchased and Retired During Period, Shares	20,000
Common Stock Shares Outstanding, Ending Balance at Jun. 30, 2020	66,221,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Profit Loss	$ 28,076,000	0	0	28,076,000
Cash dividend declared	12,920,000	0	(12,920,000)	0
Issuance of common stock pursuant to public offerings, net	15,566,000	31,000	15,535,000	0
Stock Issued During Period Value Share Based Compensation	51,000	0	51,000	0
Balances at Sep. 30, 2020	$ 376,741,000	693,000	410,521,000	(34,473,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period Shares New Issues	3,073,000
Stock Issued During Period Shares Share Based Compensation	2,000
Common Stock Shares Outstanding, Ending Balance at Sep. 30, 2020	69,296,000
Balances at Dec. 31, 2020	$ 415,291,000	761,000	432,524,000	(17,994,000)
Common Stock Shares Outstanding, Ending Balance at Dec. 31, 2020	76,073,317
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Profit Loss	$ (29,369,000)	0	0	(29,369,000)
Cash dividend declared	17,226,000	0	17,226,000	0
Issuance of common stock pursuant to public offerings, net	96,908,000	182,000	96,726,000	0
Stock Issued During Period Value Share Based Compensation	572,000	1,000	571,000	0
Balances at Mar. 31, 2021	$ 466,176,000	944,000	512,595,000	(47,363,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period Shares New Issues	18,248,000
Stock Issued During Period Shares Share Based Compensation	90,000
Common Stock Shares Outstanding, Ending Balance at Mar. 31, 2021	94,411,000
Balances at Dec. 31, 2020	$ 415,291,000	761,000	432,524,000	(17,994,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Profit Loss	(20,196,000)
Issuance of common stock pursuant to public offerings, net	398,661,000
Balances at Sep. 30, 2021	$ 730,629,000	1,533,000	767,286,000	(38,190,000)
Common Stock Shares Outstanding, Beginning Balance at Dec. 31, 2020	76,073,317
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period Shares New Issues	77,153,475
Common Stock Shares Outstanding, Ending Balance at Sep. 30, 2021	153,318,351
Balances at Mar. 31, 2021	$ 466,176,000	944,000	512,595,000	(47,363,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Profit Loss	(16,865,000)	0	0	(16,865,000)
Cash dividend declared	20,416,000	0	20,416,000	0
Issuance of common stock pursuant to public offerings, net	124,746,000	231,000	124,515,000	0
Stock Issued During Period Value Share Based Compensation	180,000	0	180,000	0
Balances at Jun. 30, 2021	$ 553,821,000	1,175,000	616,874,000	(64,228,000)
Common Stock Shares Outstanding, Beginning Balance at Mar. 31, 2021	94,411,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period Shares New Issues	23,087,000
Stock Issued During Period Shares Share Based Compensation	2,000
Common Stock Shares Outstanding, Ending Balance at Jun. 30, 2021	117,500,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Profit Loss	$ 26,038,000	0	0	26,038,000
Cash dividend declared	26,420,000	0	(26,420,000)	0
Issuance of common stock pursuant to public offerings, net	177,007,000	358,000	176,649,000	0
Stock Issued During Period Value Share Based Compensation	183,000	0	183,000	0
Balances at Sep. 30, 2021	$ 730,629,000	$ 1,533,000	$ 767,286,000	$ (38,190,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period Shares New Issues	35,818,000
Stock Issued During Period Shares Share Based Compensation	0
Common Stock Shares Outstanding, Ending Balance at Sep. 30, 2021	153,318,351