Summary of Significant Accounting Policies - Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Basic EPS
Net income attributable to common stockholders	$ 150,979	$ 111,412	$ 94,904
Weighted-Average Shares (in shares)	10,791,000	10,758,000	10,728,000
Dollars per share (in dollars per share)	$ 14.00	$ 10.36	$ 8.85
Effect of dilutive securities
SARs and restricted stock (in shares)	92,000	88,000	58,000
SARs and restricted stock (in dollars per share)	$ (0.13)	$ (0.09)	$ (0.05)
Net income, Diluted EPS	$ 150,979	$ 111,412	$ 94,904
Weighted-Average Shares, Diluted EPS (in shares)	10,883,000	10,846,000	10,786,000
Diluted EPS (in dollars per share)	$ 13.87	$ 10.27	$ 8.80
Stock Appreciation Rights and Restricted Stock
Effect of dilutive securities
Antidilutive securities excluded from earnings per share (in shares)	32,448	39,326	74,336
Performance Shares
Effect of dilutive securities
Antidilutive securities excluded from earnings per share (in shares)	18,535	18,183	12,680