Stock-Based Compensation (Outstanding and Exercisable Stock Options by Exercise Price) (Detail) shares in Thousands	12 Months Ended
Dec. 31, 2017 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award
Number of Options at Year End \| shares	2
Weighted-Average Exercise Price Per Share \| $ / shares	$ 16.5
Weighted-Average Remaining Contractual Life (in years)	2 months 12 days
Under $10.00
Share-based Compensation Arrangement by Share-based Payment Award
Number of Options at Year End \| shares	1
Weighted-Average Exercise Price Per Share \| $ / shares	$ 8.59
Weighted-Average Remaining Contractual Life (in years)	2 years
$10.01-$20.00
Share-based Compensation Arrangement by Share-based Payment Award
Number of Options at Year End \| shares	0
Weighted-Average Exercise Price Per Share \| $ / shares	$ 0
Weighted-Average Remaining Contractual Life (in years)	1 month 6 days
$20.01-$30.00
Share-based Compensation Arrangement by Share-based Payment Award
Number of Options at Year End \| shares	1
Weighted-Average Exercise Price Per Share \| $ / shares	$ 24.41
Weighted-Average Remaining Contractual Life (in years)	1 year

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No definition available.

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- Definition

The number of shares reserved for issuance pertaining to the outstanding stock options as of the balance sheet date for all option plans in the customized range of exercise prices.

+ 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 (c)(1)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

Weighted average remaining contractual term for option awards outstanding, 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 (e)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

Weighted average exercise price as of the balance sheet date for those equity-based payment arrangements exercisable and outstanding.

+ 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 (c)(1)(iii)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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