Fair Value Measurements - Carrying Amount and Estimated Fair Value of Financial Instrument Assets and Liabilities which are Not Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Level 1 [Member]
Financial Assets:
Cash and Cash Equivalents	$ 588,321	$ 655,461
Certificates of Deposit	0	0
Receivables(1)	0	0
Contract Assets(2)	0	0
Closely-held Equity Securities	0	0
Financial Liabilities:
Accounts Payable and Accrued Expenses	0	0
Payable to Employees and Related Parties	0	0
Notes Payable	0	0
Level 2 [Member]
Financial Assets:
Cash and Cash Equivalents	0	0
Certificates of Deposit	54,856	122,890
Receivables(1)	461,682	447,051
Contract Assets(2)	90,876	117,701
Closely-held Equity Securities	0	0
Financial Liabilities:
Accounts Payable and Accrued Expenses	25,989	28,807
Payable to Employees and Related Parties	45,838	41,235
Notes Payable	360,252	349,955
Level 3 [Member]
Financial Assets:
Cash and Cash Equivalents	0	0
Certificates of Deposit	0	0
Receivables(1)	0	0
Contract Assets(2)	0	0
Closely-held Equity Securities	636	604
Financial Liabilities:
Accounts Payable and Accrued Expenses	0	0
Payable to Employees and Related Parties	0	0
Notes Payable	0	0
Carrying Amount [Member]
Financial Assets:
Cash and Cash Equivalents	588,321	655,461
Certificates of Deposit	54,856	122,890
Receivables(1)	465,295	449,270
Contract Assets(2)	91,246	118,496
Closely-held Equity Securities	636	604
Financial Liabilities:
Accounts Payable and Accrued Expenses	25,989	28,807
Payable to Employees and Related Parties	45,838	41,235
Notes Payable	373,885	371,774
Total [Member]
Financial Assets:
Cash and Cash Equivalents	588,321	655,461
Certificates of Deposit	54,856	122,890
Receivables(1)	461,682	447,051
Contract Assets(2)	90,876	117,701
Closely-held Equity Securities	636	604
Financial Liabilities:
Accounts Payable and Accrued Expenses	25,989	28,807
Payable to Employees and Related Parties	45,838	41,235
Notes Payable	$ 360,252	$ 349,955