Shareholders' Equity - Schedule of Shares Granted and Vested (Details) - Share Award Plans - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of Shares
Unvested shares at the beginning of the year (in shares)	227,340	161,990	148,010
Shares awarded (in shares)	420,000	202,500	123,800
Shares vested/forfeited (in shares)	(212,790)	(137,150)	(109,820)
Unvested shares at the end of the year (in shares)	434,550	227,340	161,990
Weighted Average Award Date Fair Value
Unvested shares at the beginning of the year (in dollars per share)	$ 12.52	$ 19.41	$ 19.71
Shares awarded (in dollars per share)	3.65	8.65	18.72
Shares vested/forfeited (in dollars per share)	7.04	8.94	18.31
Unvested shares at the end of the year (in dollars per share)	$ 6.15	$ 12.52	$ 19.41