Shareholders' Equity - Unvested Shares Activity (Details) - 2009 Award Plan - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Number of Shares
Unvested at the beginning of the period (in shares)	55,321	26,062	24,743
Granted (in shares)	136,100	19,925	18,837
Forfeited (in shares)	(1,474)	(255)	0
Vested (in shares)	(83,267)	(18,634)	(17,518)
Unvested acquired in the SIR merger (in shares)	0	28,223	0
Unvested at the end of the period (in shares)	106,680	55,321	26,062
Weighted Average Grant Date Fair Value
Unvested at the beginning of the period (in dollars per share)	$ 73.25	$ 78.24	$ 82.36
Granted (in dollars per share)	28.84	64.73	77.44
Forfeited (in dollars per share)	49.10	52.96	0
Vested (in dollars per share)	27.78	63.80	83.20
Unvested acquired in the SIR merger (in dollars per share)	0	27.48	0
Unvested at the end of the period (in dollars per share)	$ 40.16	$ 73.25	$ 78.24