Consolidated Statements of Equity - USD ($)	Total	Common Stock	Additional Paid- in Capital	Common Shares Held in Deferred Compensation Plan	Deferred Compensation Plan	Deferred Compensation Plan	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning balance (in shares) at Dec. 31, 2018		61,013,711,000
Beginning balance at Dec. 31, 2018	$ 1,247,797,000	$ 610,000	$ 1,233,763,000			$ 0	$ 14,185,000	$ (761,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	15,532,000						15,532,000
Issuance of common stock, net of issuance costs (in shares)		2,184,888,000
Issuance of common stock, net of issuance costs	87,924,000	$ 22,000	87,902,000
Repurchase and cancellation of common stock related to employee awards (in shares)		(99,999,000)
Repurchase and cancellation of common stock related to employee awards	(3,959,000)		(3,959,000)
Issuance of restricted stock (in shares)		30,294,000
Stock-based compensation	928,000		928,000
Common stock dividends	(15,109,000)						(15,109,000)
Other comprehensive income	63,000							63,000
Ending balance (in shares) at Mar. 31, 2019		63,128,894,000
Ending balance at Mar. 31, 2019	1,333,176,000	$ 632,000	1,318,634,000			$ 0	14,608,000	(698,000)
Beginning balance (in shares) at Dec. 31, 2019		67,252,787
Beginning balance at Dec. 31, 2019	1,517,123,000	$ 673,000	1,514,266,000	$ 0	$ 0		2,621,000	(437,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	12,856,000						12,856,000
Issuance of common stock, net of issuance costs (in shares)		562,521
Issuance of common stock, net of issuance costs	29,651,000	$ 4,000	29,647,000
Repurchase and cancellation of common stock related to employee awards (in shares)		(4,510)
Repurchase and cancellation of common stock related to employee awards	(240,000)		(240,000)
Issuance of restricted stock (in shares)		20,501
Stock-based compensation	1,573,000		1,573,000
Common stock dividends	(18,314,000)						(18,314,000)
Deposits to deferred compensation plan (in shares)		(135,494)		135,494
Deposits to deferred compensation plan	0		7,346,000		(7,346,000)
Other comprehensive income	73,000							73,000
Ending balance (in shares) at Mar. 31, 2020		67,695,805
Ending balance at Mar. 31, 2020	$ 1,542,722,000	$ 677,000	$ 1,552,592,000	$ 135,494	$ (7,346,000)		$ (2,837,000)	$ (364,000)