Investments - Additional Information (Detail) - USD ($)	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	$ 18,000	$ 0
Marketable Securities	0	61,153,000
Debt Securities, Available-for-sale, Amortized Cost	156,774,000	139,705,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1,000	13,000
Debt Securities, Available-for-sale	156,757,000	139,718,000
Cash and Cash Equivalents, at Carrying Value	251,000,000	271,719,000	$ 114,414,000	$ 279,906,000
Long-term Investments	23,516,000	25,409,000
Aggregate cost basis for investments	19,300,000	17,200,000
Available-for-sale Securities	151,750,000
Fair Value, Net Asset (Liability)	17,983,000	19,787,000
Fair Value, Inputs, Level 1 [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	18,000	0
Marketable Securities	0	61,153,000
Debt Securities, Available-for-sale, Amortized Cost	156,774,000	139,705,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1,000	13,000
Debt Securities, Available-for-sale	156,757,000	139,718,000
Cash and Cash Equivalents, at Carrying Value	156,757,000	94,226,000
U.S. non-qualified deferred compensation plan assets	23,516,000	25,409,000
Fair Value, Inputs, Level 2 [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Defined Benefit Plan, Plan Assets, Amount	15,053,000	15,296,000
Defined Benefit Plan, Benefit Obligation	(20,586,000)	(20,918,000)
Fair Value, Net Asset (Liability)	(5,533,000)	(5,622,000)
Other Current Liabilities [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Fair Value, Net Asset (Liability)	(1,297,000)	(1,318,000)
Other Current Liabilities [Member] | Fair Value, Inputs, Level 1 [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Available-for-sale Securities	0	0
Other Current Liabilities [Member] | Fair Value, Inputs, Level 2 [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Defined Benefit Plan, Benefit Obligation	(1,297,000)	(1,318,000)
Fair Value, Net Asset (Liability)	(1,297,000)	(1,318,000)
Assets Designated for Retirement and Pension Plans [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Fair Value, Net Asset (Liability)	13,756,000	13,978,000
Assets Designated for Retirement and Pension Plans [Member] | Fair Value, Inputs, Level 1 [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
U.S. non-qualified deferred compensation plan assets	0	0
Assets Designated for Retirement and Pension Plans [Member] | Fair Value, Inputs, Level 2 [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Defined Benefit Plan, Plan Assets, Amount	13,756,000	13,978,000
Defined Benefit Plan, Benefit Obligation	0	0
Fair Value, Net Asset (Liability)	13,756,000	13,978,000
Investments [Domain]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Available-for-sale Securities	0
Fair Value, Net Asset (Liability)	23,516,000	25,409,000
Investments [Domain] | Fair Value, Inputs, Level 1 [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
U.S. non-qualified deferred compensation plan assets	23,516,000	25,409,000
Investments [Domain] | Fair Value, Inputs, Level 2 [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Defined Benefit Plan, Benefit Obligation	0	0
Fair Value, Net Asset (Liability)	0	0
Other Pension Plan [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Fair Value, Net Asset (Liability)	(19,289,000)	(19,600,000)
Other Pension Plan [Member] | Fair Value, Inputs, Level 1 [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Available-for-sale Securities	0	0
Other Pension Plan [Member] | Fair Value, Inputs, Level 2 [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Defined Benefit Plan, Benefit Obligation	(19,289,000)	(19,600,000)
Fair Value, Net Asset (Liability)	(19,289,000)	(19,600,000)
Other Current Assets [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Fair Value, Net Asset (Liability)	1,297,000	1,318,000
Other Current Assets [Member] | Fair Value, Inputs, Level 1 [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
U.S. non-qualified deferred compensation plan assets	0	0
Other Current Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Defined Benefit Plan, Plan Assets, Amount	1,297,000	1,318,000
Defined Benefit Plan, Benefit Obligation	0	0
Fair Value, Net Asset (Liability)	$ 1,297,000	$ 1,318,000