Summary of Significant Accounting Policies - Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Basic EPS
Net income attributable to common stockholders	$ 34,627	$ 28,531	$ 114,352	$ 84,351
Weighted-Average Shares (in shares)	10,799,000	10,766,000	10,787,000	10,756,000
Dollars per share (in dollars per share)	$ 3.21	$ 2.65	$ 10.61	$ 7.84
Effect of dilutive securities
SARs and restricted stock (in shares)	75,000	76,000	88,000	78,000
SARs and restricted stock (in dollars per share)	$ (0.03)	$ (0.02)	$ (0.10)	$ (0.05)
Net income, Diluted EPS	$ 34,627	$ 28,531	$ 114,352	$ 84,351
Weighted-Average Shares, Diluted EPS (in shares)	10,874,000	10,842,000	10,875,000	10,834,000
Diluted EPS (in dollars per share)	$ 3.18	$ 2.63	$ 10.51	$ 7.79
Stock Appreciation Rights and Restricted Stock
Effect of dilutive securities
Antidilutive securities excluded from earnings per share (in shares)	18,432	28,575	37,120	52,434
Performance Shares
Effect of dilutive securities
Antidilutive securities excluded from earnings per share (in shares)	18,535	18,183		18,183