Stockholders' Equity - Common Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Shares Issued
Dividend reinvestment plan issuances (in shares)		264,153
Option exercises (in shares)		251
ATM Program issuances (in shares)	17,720,008	6,799,978
Stock incentive plans, net of forfeitures (in shares)	153,275	185,994
Totals (in shares)	17,873,283	7,250,376
Average Price
Dividend reinvestment plan issuances (in dollars per share)		$ 72.33
Option exercises (in dollars per share)		47.81
ATM Program issuances (in dollars per share)	$ 77.91	$ 86.48
Gross Proceeds
Dividend reinvestment plan issuances		$ 19,105
Option exercises		12
ATM Program issuances	$ 1,380,519	588,072
Totals	1,380,519	607,189
Net Proceeds
Dividend reinvestment plan issuances		19,105
Option exercises		12
ATM Program issuances	1,366,464	576,196
Total	$ 1,366,464	$ 595,313