Stockholders' Equity (ATM Program) (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Class of Stock [Line Items]
Total allowable shares (in shares)	375,000,000		375,000,000
Total shares issued (in shares)	173,726,996		171,694,209
Net proceeds	$ 65,440	$ 539,318
Stock issuance costs	$ 7,810	$ 115
ATM equity programs
Class of Stock [Line Items]
Shares of common stock (in shares)	1,634,350	2,344,022
Average price per share (net) (in dollars per share)	$ 36.56	$ 53.73
Net proceeds	$ 59,752	$ 125,946
Stock issuance costs	$ 1,151	$ 1,390
2018 ATM
Class of Stock [Line Items]
Total allowable shares (in shares)	12,000,000
Total shares issued (in shares)	11,272,034
2020 ATM
Class of Stock [Line Items]
Total allowable shares (in shares)	17,500,000
Total shares issued (in shares)	84,501