Stock-based Compensation Plans - Additional Information 4 (Detail) - USD ($) shares in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Deferred compensation plan vesting period	3 years
Deferred compensation plan	$ 8,537,000	$ (3,581,000)
Shares held in rabbi trust total	6.4		3.2
Vested shares held in rabbi trust	3.2		2.7
Post-Retirement Medical Plan
Defined Benefit Plan Disclosure [Line Items]
Estimated prior service cost amortized from accumulated other comprehensive income into general and administrative expense	$ 92,000	$ 92,000

Amount of prior service cost (credit) recognized in net periodic benefit cost (credit) of defined benefit plan.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (h)(5)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (a)(5)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2709-114920

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