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	Jun. 30, 2022	Dec. 31, 2021
Level 1 [Member]
Financial Assets:
Cash and Cash Equivalents	$ 438,420	$ 575,317
Certificates of Deposit, at Carrying Value	0	0
Receivables(1)	0	0
Contract Assets(2)	0	0
Receivable from Employees and Related Parties	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, at Carrying Value	148,563	141,218
Receivables(1)	379,522	436,749
Contract Assets(2)	66,717	25,986
Receivable from Employees and Related Parties	21,207	25,208
Financial Liabilities:
Accounts Payable and Accrued Expenses	38,224	31,633
Payable to Employees and Related Parties	56,436	58,876
Notes Payable	369,191	390,288
Level 3 [Member]
Financial Assets:
Cash and Cash Equivalents	0	0
Certificates of Deposit, at Carrying Value	0	0
Receivables(1)	0	0
Contract Assets(2)	0	0
Receivable from Employees and Related Parties	0	0
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	438,420	575,317
Certificates of Deposit, at Carrying Value	148,563	141,218
Receivables(1)	381,336	439,432
Contract Assets(2)	66,807	27,037
Receivable from Employees and Related Parties	21,207	25,208
Financial Liabilities:
Accounts Payable and Accrued Expenses	38,224	31,633
Payable to Employees and Related Parties	56,436	58,876
Notes Payable	371,707	376,243
Total [Member]
Financial Assets:
Cash and Cash Equivalents	438,420	575,317
Certificates of Deposit, at Carrying Value	148,563	141,218
Receivables(1)	379,522	436,749
Contract Assets(2)	66,717	25,986
Receivable from Employees and Related Parties	21,207	25,208
Financial Liabilities:
Accounts Payable and Accrued Expenses	38,224	31,633
Payable to Employees and Related Parties	56,436	58,876
Notes Payable	369,191	390,288
Equity Securities [Member] | Level 1 [Member]
Financial Assets:
Investments	0	0
Equity Securities [Member] | Level 2 [Member]
Financial Assets:
Investments	0	0
Equity Securities [Member] | Level 3 [Member]
Financial Assets:
Investments	608	676
Equity Securities [Member] | Carrying Amount [Member]
Financial Assets:
Investments	608	676
Equity Securities [Member] | Total [Member]
Financial Assets:
Investments	$ 608	$ 676