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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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-Subparagraph (a)(1)
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No definition available.

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- Definition

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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- Definition

Period from grant date that an equity-based award expires, 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
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-Name Accounting Standards Codification
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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Share-Based Payment (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock options
Fair value assumptions, Black-Scholes
Expiration period	10 years
Vesting period	3 years
Expected dividend yield	0.00%	0.00%	0.00%
Stock options \| Officers And Employees
Fair value assumptions, Black-Scholes
Vesting period	3 years
RSUs \| 2014 PSP
Fair value assumptions, Black-Scholes
Vesting period	3 years
RSUs \| 2016 PSP
Fair value assumptions, Black-Scholes
Vesting period	3 years
RSUs \| 2017 PSP
Fair value assumptions, Black-Scholes
Vesting period	3 years
Restricted shares \| Officers And Employees
Fair value assumptions, Black-Scholes
Vesting period	3 years
Restricted shares \| Non-Employee Directors
Fair value assumptions, Black-Scholes
Vesting period	1 year