Shareholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock Value Authorized Under Stock Offering Program	$ 400,000
Stock Issued During Period, Shares, New Issues	4,600,000	8,000,000.0	990,400
Proceeds from issuance of common shares, net	$ 187,856	$ 272,761	$ 34,913
At-the-market equity issuance [Member]
Proceeds from issuance of common shares, net	175,000	263,300	28,400
Gross Proceeds [Member] | At-the-market equity issuance [Member]
Proceeds from issuance of common shares, net	$ 177,100	$ 266,300	$ 29,000