Fair Value Disclosure (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized gain (loss) on equity securities	$ 1,041	$ 628
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair value measurements, recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	18,284		$ 17,208
Unrealized gain (loss) on equity securities	400	100
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair value measurements, recurring | Bellaire
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized gain (loss) on equity securities	700	$ 600
Quoted Prices in Active Markets for Identical Assets (Level 1) | Reported Value Measurement | Fair value measurements, recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities cost				$ 2,000
Quoted Prices in Active Markets for Identical Assets (Level 1) | Reported Value Measurement | Fair value measurements, recurring | Other noncurrent assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	6,400		6,000
Quoted Prices in Active Markets for Identical Assets (Level 1) | Reported Value Measurement | Fair value measurements, recurring | Bellaire
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities cost				$ 5,000
Quoted Prices in Active Markets for Identical Assets (Level 1) | Reported Value Measurement | Fair value measurements, recurring | Bellaire | Other noncurrent assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	$ 11,900		$ 11,200