Fair Value Measurements (Fair Value of Financial Assets and Liabilities) (Details 1) - USD ($) $ in Thousands		Mar. 31, 2026	Dec. 31, 2025
Assets
Money Market Investments		$ 7,500	$ 5,300
Marketable equity securities		966,719	1,081,938
Fair Value, Recurring [Member]
Assets
Money Market Investments	[1]	7,527	5,251
Marketable equity securities	[2]	966,719	1,081,938
Other current investments	[3]	5,982	7,032
Total Financial Assets		980,228	1,094,221
Liabilities
Contingent consideration liabilities	[4]	1,223	1,526
Interest rate swaps	[5]	1,672	2,289
Mandatorily redeemable noncontrolling interest	[6]	7,636	8,401
Total Financial Liabilities		10,531	12,216
Level 1 | Fair Value, Recurring [Member]
Assets
Money Market Investments	[1]	0	0
Marketable equity securities	[2]	966,719	1,081,938
Other current investments	[3]	0	0
Total Financial Assets		966,719	1,081,938
Liabilities
Contingent consideration liabilities	[4]	0	0
Interest rate swaps	[5]	0	0
Mandatorily redeemable noncontrolling interest	[6]	0	0
Total Financial Liabilities		0	0
Level 2 | Fair Value, Recurring [Member]
Assets
Money Market Investments	[1]	7,527	5,251
Marketable equity securities	[2]	0	0
Other current investments	[3]	5,982	7,032
Total Financial Assets		13,509	12,283
Liabilities
Contingent consideration liabilities	[4]	0	0
Interest rate swaps	[5]	1,672	2,289
Mandatorily redeemable noncontrolling interest	[6]	0	0
Total Financial Liabilities		1,672	2,289
Level 3 | Fair Value, Recurring [Member]
Assets
Money Market Investments	[1]	0	0
Marketable equity securities	[2]	0	0
Other current investments	[3]	0	0
Total Financial Assets		0	0
Liabilities
Contingent consideration liabilities	[4]	1,223	1,526
Interest rate swaps	[5]	0	0
Mandatorily redeemable noncontrolling interest	[6]	7,636	8,401
Total Financial Liabilities		$ 8,859	$ 9,927

[1] The Company’s money market investments are included in cash and cash equivalents and the value considers the liquidity of the counterparty.

[2] The Company’s investments in marketable equity securities are held in common shares of U.S. corporations that are actively traded on U.S. stock exchanges. Price quotes for these shares are readily available.

[3] Includes mutual funds, which are valued using a market approach based on the quoted market prices of the security or inputs that include quoted market prices for similar instruments.

[4] Included in Current liabilities held for sale and Noncurrent liabilities held for sale as of March 31, 2026. The balances were included in Accounts payable, vehicle floor plan payable and accrued liabilities and Other Liabilities as of December 31, 2025. The Company determined the fair value of the contingent consideration liabilities using either a Monte Carlo simulation, Black-Scholes model, or probability-weighted analysis depending on the type of target included in the contingent consideration requirements (revenue, EBITDA, client retention). All analyses included estimated financial projections for the acquired businesses and acquisition-specific discount rates.

[5] Included in Other Liabilities. The Company utilized a market approach model using the notional amount of the interest rate swaps multiplied by the observable inputs of time to maturity and market interest rates.

[6] The fair value of the mandatorily redeemable noncontrolling interest is based on the fair value of the underlying subsidiaries owned by GHC One and GHC Two, after taking into account any debt and other noncontrolling interests of its subsidiary investments. The fair value of the owned subsidiaries is determined using enterprise value analyses which include an equal weighing between guideline public company and discounted cash flow analyses.