Common and Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended			3 Months Ended					6 Months Ended		8 Months Ended	12 Months Ended
	Jun. 30, 2021	Jan. 31, 2021	Apr. 30, 2020	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2020	May 31, 2021	Apr. 30, 2021	Feb. 28, 2021	Jul. 31, 2019
Class of Stock [Line Items]
Common stock, shares authorized	180,000,000			180,000,000					180,000,000		90,000,000	90,000,000	180,000,000	90,000,000
Proceeds from common stock offerings, net									$ 594,980	$ 541,715
Preferred stock, par value (in dollars per share)	$ 0.0001			$ 0.0001					$ 0.0001		$ 0.0001	$ 0.0001
Preferred stock, shares authorized	4,000,000			4,000,000					4,000,000		4,000,000	4,000,000
Common Stock [Member]
Class of Stock [Line Items]
Common stock, shares authorized			2,875,000
Issuance of common stock, net of issuance costs (in shares)				4,764,450	4,028,410	6,851,695	1,400,251
Proceeds from common stock offerings, net			$ 170,400
Common Stock [Member] | Forward Sale Agreement [Member]
Class of Stock [Line Items]
Common stock, shares authorized	4,600,000	3,450,000	6,166,666	4,600,000					4,600,000
Proceeds from common stock offerings, net	$ 327,000										$ 354,600
At-Market Equity Program [Member] | Common Stock [Member]
Class of Stock [Line Items]
Forward Contract Indexed to Issuer's Equity, Shares							3,169,754
At-Market Equity Program Two [Member] | Common Stock [Member]
Class of Stock [Line Items]
Forward Contract Indexed to Issuer's Equity, Shares								2,003,118
Proceeds from common stock offerings, net												$ 359,500
Value Of Equity Instruments To Be Issued																$ 400,000
At-Market Equity Program Three [Member] | Common Stock [Member]
Class of Stock [Line Items]
Value Of Equity Instruments To Be Issued	$ 0			$ 0					$ 0
At-Market Equity Program Four [Member] | Common Stock [Member]
Class of Stock [Line Items]
Forward Contract Indexed to Issuer's Equity, Shares												3,334,056
Issuance of common stock, net of issuance costs (in shares)									742,860			204,074
Proceeds from common stock offerings, net									$ 46,800			$ 12,500
Value Of Equity Instruments To Be Issued							$ 400,000
At-Market Equity Program Five [Member] | Common Stock [Member]
Class of Stock [Line Items]
Forward Contract Indexed to Issuer's Equity, Shares									1,550,666
Issuance of common stock, net of issuance costs (in shares)									0
Value Of Equity Instruments To Be Issued															$ 500,000
Over-Allotment Option [Member] | Common Stock [Member]
Class of Stock [Line Items]
Common stock, shares authorized			375,000
Over-Allotment Option [Member] | Common Stock [Member] | Forward Sale Agreement [Member]
Class of Stock [Line Items]
Common stock, shares authorized	600,000	450,000		600,000					600,000
Common Stock [Member] | Forward Sale Agreement [Member]
Class of Stock [Line Items]
Proceeds from common stock offerings, net		$ 221,400
Common Stock [Member] | At-Market Equity Program Four [Member]
Class of Stock [Line Items]
Value Of Equity Instruments To Be Issued	$ 0			$ 0					$ 0