Fair Value Measurements (Details 1) - USD ($)		Sep. 30, 2019	Dec. 31, 2018
Assets
Money Market Investments		$ 0	$ 75,500,000
Marketable equity securities		535,564,000	496,390,000
Fair Value, Recurring [Member]
Assets
Money Market Investments	[1]		75,500,000
Marketable equity securities	[2]	535,564,000	496,390,000
Other current investments	[3]	18,646,000	18,191,000
Interest Rate Swap	[4]	162,000	369,000
Total Financial Assets		554,372,000	590,450,000
Liabilities
Deferred compensation plan liabilities	[5]	33,195,000	36,080,000
Interest rate swap	[6]	706,000
Total Financial Liabilities		33,901,000
Fair Value, Recurring [Member] | Level 1 [Member]
Assets
Money Market Investments	[1]		0
Marketable equity securities	[2]	535,564,000	496,390,000
Other current investments	[3]	13,601,000	11,203,000
Interest Rate Swap	[4]	0	0
Total Financial Assets		549,165,000	507,593,000
Liabilities
Deferred compensation plan liabilities	[5]	0	0
Interest rate swap	[6]	0
Total Financial Liabilities		0
Fair Value, Recurring [Member] | Level 2 [Member]
Assets
Money Market Investments	[1]		75,500,000
Marketable equity securities	[2]	0	0
Other current investments	[3]	5,045,000	6,988,000
Interest Rate Swap	[4]	162,000	369,000
Total Financial Assets		5,207,000	82,857,000
Liabilities
Deferred compensation plan liabilities	[5]	33,195,000	$ 36,080,000
Interest rate swap	[6]	706,000
Total Financial Liabilities		$ 33,901,000

[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 U.S. Government Securities, corporate bonds, mutual funds and time deposits. These investments 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 and are classified as either Level 1 or Level 2 in the fair value hierarchy.

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

[5] Includes Graham Holdings Company’s Deferred Compensation Plan and supplemental savings plan benefits under the Graham Holdings Company’s Supplemental Executive Retirement Plan, which are included in accrued compensation and related benefits. These plans measure the market value of a participant’s balance in a notional investment account that is comprised primarily of mutual funds, which are based on observable market prices. However, since the deferred compensation obligations are not exchanged in an active market, they are classified as Level 2 in the fair value hierarchy. Realized and unrealized gains (losses) on deferred compensation are included in operating income.

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