Stockholders' Equity (ATM Program) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Class of Stock [Line Items]
Total allowable shares (in shares)	375,000,000		375,000,000
Total shares issued (in shares)	175,579,683		175,232,971
Net proceeds	$ 1,882	$ 696
Stock issuance costs	$ 5,145	$ 6,397
ATM equity programs
Class of Stock [Line Items]
Shares of common stock (in shares)	30,000
Average price per share (net) (in dollars per share)	$ 38.59
Net proceeds	$ 1,158
Stock issuance costs	$ 75
2020 ATM
Class of Stock [Line Items]
Total allowable shares (in shares)	17,500,000
Total shares issued (in shares)	1,599,304
2018 ATM
Class of Stock [Line Items]
Total allowable shares (in shares)	12,000,000
Total shares issued (in shares)	11,272,034