Schedule of Share-based Compensation, Stock Options, Activity (Detail) - $ / shares shares in Thousands	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Shares
Outstanding at January 1	265	546	3,877
Exercised	(126)	(115)	(190)
Forfeited or expired	(20)	(166)	(3,141)
Outstanding at December 31	119	265	546
Exercisable at December 31	119	265	546
Weighted-Average Grant Price
Outstanding at January 1	$ 14.25	$ 20.72	$ 45.00
Exercised	13.67	12.84	11.88
Forfeited or expired	13.59	36.42	51.23
Outstanding at December 31	14.97	14.25	20.72
Exercisable at December 31	$ 14.97	$ 14.25	$ 20.72

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

+ References

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

+ References

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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-Publisher FASB
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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Number of share options (or share units) exercised during the current period.

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