Investments and Fair Value Measurements (Fair Value Measurements) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Assets:
Debt securities available for sale	$ 73,225	$ 81,643
Total investment securities at fair value	110,935	116,436
Long-term investment securities at fair value	29,402	28,919
Marketable equity securities
Assets:
Equity securities at fair value:	14,286	12,724
Mutual funds invested in debt securities
Assets:
Equity securities at fair value:	23,424	22,069
U.S. Government securities
Assets:
Debt securities available for sale	38,657
Corporate securities
Assets:
Debt securities available for sale	12,042
U.S. mortgage-backed securities
Assets:
Debt securities available for sale	17,358
Commercial paper
Assets:
Debt securities available for sale	5,168
Recurring
Assets:
Total	407,139	379,292
Recurring | Fair Value, Inputs, Level 1, Level 2, and Level 3
Assets:
Total investment securities at fair value	110,935	116,436
Recurring | Fair Value, Inputs, Level 1, Level 2, and Level 3 | Total equity securities at fair value
Assets:
Equity securities at fair value:	37,710	34,793
Recurring | Fair Value, Inputs, Level 1, Level 2, and Level 3 | Marketable equity securities
Assets:
Equity securities at fair value:	14,286	12,724
Recurring | Fair Value, Inputs, Level 1, Level 2, and Level 3 | Mutual funds invested in debt securities
Assets:
Equity securities at fair value:	23,424	22,069
Recurring | Fair Value, Inputs, Level 1, Level 2, and Level 3 | Total debt securities available for sale
Assets:
Debt securities available for sale	73,225	81,643
Recurring | Fair Value, Inputs, Level 1, Level 2, and Level 3 | U.S. Government securities
Assets:
Debt securities available for sale	38,657	779
Recurring | Fair Value, Inputs, Level 1, Level 2, and Level 3 | Corporate securities
Assets:
Debt securities available for sale	12,042	53,814
Recurring | Fair Value, Inputs, Level 1, Level 2, and Level 3 | U.S. mortgage-backed securities
Assets:
Debt securities available for sale	17,358	27,050
Recurring | Fair Value, Inputs, Level 1, Level 2, and Level 3 | Commercial paper
Assets:
Debt securities available for sale	5,168
Recurring | Fair Value, Inputs, Level 1, Level 2, and Level 3 | Index-linked U.S. bonds
Assets:
Debt securities available for sale	0
Recurring | Fair Value, Inputs, Level 1, Level 2, and Level 3 | Money market funds
Assets:
Cash and cash equivalents	214,515	155,411
Recurring | Fair Value, Inputs, Level 1, Level 2, and Level 3 | Commercial paper
Assets:
Cash and cash equivalents	52,287	54,526
Recurring | Fair Value, Inputs, Level 1, Level 2, and Level 3 | Money market funds securing legal bonds
Assets:
Cash and cash equivalents		24,000
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Total investment securities at fair value	37,710	34,793
Total	252,225	214,204
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Total equity securities at fair value
Assets:
Equity securities at fair value:	37,710	34,793
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Marketable equity securities
Assets:
Equity securities at fair value:	14,286	12,724
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mutual funds invested in debt securities
Assets:
Equity securities at fair value:	23,424	22,069
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Total debt securities available for sale
Assets:
Debt securities available for sale	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Government securities
Assets:
Debt securities available for sale	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate securities
Assets:
Debt securities available for sale	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. mortgage-backed securities
Assets:
Debt securities available for sale	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Commercial paper
Assets:
Debt securities available for sale	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Index-linked U.S. bonds
Assets:
Debt securities available for sale	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Money market funds
Assets:
Cash and cash equivalents	214,515	155,411
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Commercial paper
Assets:
Cash and cash equivalents	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Money market funds securing legal bonds
Assets:
Cash and cash equivalents		24,000
Recurring | Significant Other Observable Inputs (Level 2)
Assets:
Total investment securities at fair value	73,225	81,643
Total	125,512	136,169
Recurring | Significant Other Observable Inputs (Level 2) | Total equity securities at fair value
Assets:
Equity securities at fair value:	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Marketable equity securities
Assets:
Equity securities at fair value:	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Mutual funds invested in debt securities
Assets:
Equity securities at fair value:	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Total debt securities available for sale
Assets:
Debt securities available for sale	73,225	81,643
Recurring | Significant Other Observable Inputs (Level 2) | U.S. Government securities
Assets:
Debt securities available for sale	38,657	779
Recurring | Significant Other Observable Inputs (Level 2) | Corporate securities
Assets:
Debt securities available for sale	12,042	53,814
Recurring | Significant Other Observable Inputs (Level 2) | U.S. mortgage-backed securities
Assets:
Debt securities available for sale	17,358	27,050
Recurring | Significant Other Observable Inputs (Level 2) | Commercial paper
Assets:
Debt securities available for sale	5,168
Recurring | Significant Other Observable Inputs (Level 2) | Index-linked U.S. bonds
Assets:
Debt securities available for sale	0
Recurring | Significant Other Observable Inputs (Level 2) | Money market funds
Assets:
Cash and cash equivalents	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Commercial paper
Assets:
Cash and cash equivalents	52,287	54,526
Recurring | Significant Other Observable Inputs (Level 2) | Money market funds securing legal bonds
Assets:
Cash and cash equivalents		0
Recurring | Significant Unobservable Inputs (Level 3)
Assets:
Total investment securities at fair value	0	0
Total	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Total equity securities at fair value
Assets:
Equity securities at fair value:	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Marketable equity securities
Assets:
Equity securities at fair value:	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Mutual funds invested in debt securities
Assets:
Equity securities at fair value:	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Total debt securities available for sale
Assets:
Debt securities available for sale	0	0
Recurring | Significant Unobservable Inputs (Level 3) | U.S. Government securities
Assets:
Debt securities available for sale	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Corporate securities
Assets:
Debt securities available for sale	0	0
Recurring | Significant Unobservable Inputs (Level 3) | U.S. mortgage-backed securities
Assets:
Debt securities available for sale	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Commercial paper
Assets:
Debt securities available for sale	0
Recurring | Significant Unobservable Inputs (Level 3) | Index-linked U.S. bonds
Assets:
Debt securities available for sale	0
Recurring | Significant Unobservable Inputs (Level 3) | Money market funds
Assets:
Cash and cash equivalents	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Commercial paper
Assets:
Cash and cash equivalents	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Money market funds securing legal bonds
Assets:
Cash and cash equivalents		0
Recurring | NAV
Assets:
Long-term investment securities at fair value	$ 29,402	$ 28,919