CAPITAL STOCK - Additional Information (Detail) - USD ($) shares in Millions, $ in Millions	6 Months Ended	140 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018
Equity, Class of Treasury Stock [Line Items]
Number of shares repurchased under settlement of employee tax withholding obligations	0.1	0.1
Shares repurchased aggregate value under settlement of employee tax withholding obligations	$ 5.4	$ 2.8
2006 Share Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Share repurchase program	$ 1,000.0		$ 1,000.0
Repurchase of shares of common stock	1.0	0.8	22.1
Aggregate cost of repurchase	$ 50.0	$ 30.0	$ 909.4

Number of shares repurchased under settlement of employee tax withholding obligations.

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- Definition

Shares repurchased aggregate value under settlement of employee tax withholding obligations.

+ References

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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.

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Amount of stock repurchase plan authorized.

+ References

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- Definition

Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

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Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

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