Marketable Securities and Investments (Tables)

12 Months Ended

Dec. 31, 2019

Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]

Schedule of Fair Value of Separate Accounts by Major Category of Investment [Table Text Block]

The following tables provide a summary of the fair value measurements for each major category of investments, assets designated for retirement and pension plans and associated liabilities measured at fair value on a recurring basis:

				Balance Sheet Classification
	Fair Value			Other Current Assets		Assets Designated for Retirement and Pension Plans		Investments		Other Current Liabilities			Retirement and Pension Plans
Balance at December 31, 2019
Level 1:
U.S. non-qualified deferred compensation plan	$	25,409		$	—	$	—	$	25,409	$	—		$	—
Level 2:
Retirement and pension plan assets	15,296			1,318		13,978		—		—			—
Pension benefit obligation	(20,918		)	—		—		—		(1,318		)	(19,600		)
Total Level 2	(5,622		)	1,318		13,978		—		(1,318		)	(19,600		)
Total	$	19,787		$	1,318	$	13,978	$	25,409	$	(1,318	)	$	(19,600	)

				Balance Sheet Classification
	Fair Value			Other Current Assets		Assets Designated for Retirement and Pension Plans		Investments		Other Current Liabilities			Retirement and Pension Plans
Balance at December 31, 2018
Level 1:
U.S. non-qualified deferred compensation plan	$	19,442		$	—	$	—	$	19,442	$	—		$	—
Level 2:
Retirement and pension plan assets	16,384			1,349		15,035		—		—			—
Pension benefit obligation	(20,908		)	—		—		—		(1,349		)	(19,559		)
Total Level 2	(4,524		)	1,349		15,035		—		(1,349		)	(19,559		)
Total	$	14,918		$	1,349	$	15,035	$	19,442	$	(1,349	)	$	(19,559	)