Summary of Significant Accounting Policies - Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Earnings Per Share, Basic [Abstract]
Net income attributable to common stockholders	$ 39,104	$ 25,444	$ 80,150	$ 53,402
Weighted-Average Shares (in shares)	10,796,000	10,763,000	10,782,000	10,751,000
Dollars per share (in dollars per share)	$ 3.62	$ 2.36	$ 7.43	$ 4.96
Effect of dilutive securities
SARs and restricted stock (in shares)	68,000	75,000	94,000	78,000
SARs and restricted stock (in dollars per share)	$ (0.02)	$ (0.01)	$ (0.06)	$ (0.03)
Net income, Diluted EPS	$ 39,104	$ 25,444	$ 80,150	$ 53,402
Weighted-Average Shares, Diluted EPS (in shares)	10,864,000	10,838,000	10,876,000	10,829,000
Diluted EPS (in dollars per share)	$ 3.60	$ 2.35	$ 7.37	$ 4.93
Stock Appreciation Rights and Restricted Stock
Effect of dilutive securities
Antidilutive securities excluded from earnings per share (in shares)	42,922	29,043	46,464	64,364
Performance Shares
Effect of dilutive securities
Antidilutive securities excluded from earnings per share (in shares)	18,535	18,183		18,183