Share-Based Compensation - Restricted shares based on performance conditions (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2020	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Performance based restricted shares
Share-Based Compensation
Shares awarded during period	59,490
Vesting period	3 years
Aggregate fair value at grant date	$ 8.8
Restricted shares outstanding
Outstanding at the beginning of the period (in shares))		20,000
Granted (in shares)	59,490
Vested (in shares)		(20,000)
Outstanding at the end of the period (in shares)		0	20,000
Weighted-Average Grant-Date Fair Value
Outstanding at the beginning of the period (in dollars per share)		$ 148.00
Vested (in dollars per share)				$ 148.00
Outstanding at the end of the period (in dollars per share)		$ 0	$ 148.00
Performance based restricted stock units
Share-Based Compensation
Shares awarded during period		60,633	49,065	95,902
Vesting period		3 years
Restricted shares outstanding
Outstanding at the beginning of the period (in shares))		113,000
Granted (in shares)		60,633	49,065	95,902
Vested (in shares)		(59,000)
Forfeited (in shares)		(12,000)
Outstanding at the end of the period (in shares)		103,000	113,000
Weighted-Average Grant-Date Fair Value
Outstanding at the beginning of the period (in dollars per share)		$ 85.31
Granted (in dollars per share)		121.61
Vested (in dollars per share)		96.85
Forfeited (in dollars per share)		146.36
Outstanding at the end of the period (in dollars per share)		$ 92.84	$ 85.31
Performance based restricted stock units | Minimum
Weighted-Average Grant-Date Fair Value
Vesting percentage		30.00%
Performance based restricted stock units | Maximum
Weighted-Average Grant-Date Fair Value
Vesting percentage		200.00%