Stockholders' Equity (ATM Program) (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 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)	175,598,569		175,232,971
Net proceeds	$ 2,606	$ 54,084
Stock issuance costs	$ 12,743	$ 7,809
ATM equity programs
Class of Stock [Line Items]
Shares of common stock (in shares)	30,000	1,417,977
Average price per share (net) (in dollars per share)	$ 37.05	$ 36.68
Net proceeds	$ 1,111	$ 52,018
Stock issuance costs	$ 122	$ 746
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