Stockholders' Equity - Common Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Shares Issued
Dividend reinvestment plan issuances (in shares)		175,129
Equity shelf program issuances (in shares)		6,799,978
Stock incentive plans, net of forfeitures (in shares)	119,818	158,818
Totals (in shares)	119,818	7,133,925
Average Price
Dividend reinvestment plan issuances (in dollars per share)		$ 84.54
Equity shelf plan issuances (in dollars per share)		86.48
Gross Proceeds
Dividend reinvestment plan issuances		$ 14,805
Equity shelf plan issuances		588,072
Totals	$ 0	602,877
Net Proceeds
Dividend reinvestment plan issuances		14,805
Equity shelf plan issuances		576,196
Totals	$ 0	$ 591,001