Equity-Based Compensation, Profit Sharing and Deferred Compensation Plans - Summary of Equity-Based Compensation Plans with Grants Outstanding (Textual) (Detail) - shares	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding	916,000	1,076,000
2010 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized	700,000
Shares Available to Issue	38,000
2010 Equity Incentive Plan \| RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized	240,000
Restricted share units outstanding	10,000	16,000
2010 Equity Incentive Plan \| Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding	208,000
Restricted share units vesting period or option vesting period	4 years
2014 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized	950,000
Shares Available to Issue	276,000
2014 Plan \| Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of options vesting rights	25.00%
Performance metric period	3 years
Restricted share units vesting period or option vesting period	4 years
2014 Plan \| Options \| Option Grant Solely Contingent upon Continued Employment or Continued Service as a Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of options vesting rights	50.00%
2014 Plan \| Options \| Option Grant Contingent upon Continued Employment or Service as a Director and Achievement of Performance Metric
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of options vesting rights	50.00%

Performance metric based on return on capital performance period.

No definition available.

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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

No definition available.

+ Details

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- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

+ References

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- Definition

Number of options outstanding, including both vested and non-vested options.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

Percentage of vesting of share-based compensation awards.

+ References

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