SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Basic EPS
Net income attributable to common stockholders	$ 58,877	$ 49,170	$ 110,709	$ 93,155
Net income attributable to common stockholders (in shares)	10,849,000	10,933,000	10,847,000	10,915,000
Net income attributable to common stockholders (in dollars per share)	$ 5.43	$ 4.50	$ 10.21	$ 8.53
Effect of dilutive securities
SARs and restricted stock units (in shares)	33,000	30,000	55,000	58,000
SARs and restricted stock units (in dollars per share)	$ (0.02)	$ (0.02)	$ (0.06)	$ (0.04)
Net income, diluted EPS	$ 58,877	$ 49,170	$ 110,709	$ 93,155
Weighted-average shares, diluted EPS (in shares)	10,882,000	10,963,000	10,902,000	10,973,000
Diluted EPS (in dollars per share)	$ 5.41	$ 4.48	$ 10.15	$ 8.49
Stock Appreciation Rights and Restricted Stock
Effect of dilutive securities
Antidilutive securities excluded from earnings per share (in shares)	56,568	76,166	48,646	67,353
Performance Shares
Effect of dilutive securities
Antidilutive securities excluded from earnings per share (in shares)	10,962	29,507	10,962	29,507