CONTRIBUTING EMPLOYEE OWNERSHIP PLAN (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan Expense	$ 29.0	$ 28.2	$ 18.1
Defined Contribution Plan Matching Expense	$ 11.5	$ 11.2	$ 6.9
Initial vesting period (in years)	2
Initial vesting period vested percentage	25.00%
Additional vesting percentage for each additional year of service	25.00%
Years of service for full vesting	5
Vesting percentage after five years	100.00%
Number of days an employee is prohibited from trading out of the fund to which the transfer was made	7
Minimum
Defined Contribution Plan Disclosure [Line Items]
Contribution To Individual Retirement Account Percentage Of Employees Eligible Compensation	5.00%
Maximum
Defined Contribution Plan Disclosure [Line Items]
Contribution To Individual Retirement Account Percentage Of Employees Eligible Compensation	10.00%

Additional vesting percentage for each year of service, after the initial two years of service.

No definition available.

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- Definition

Minimum term of service before an employee becomes vested in the plan.

+ References

No definition available.

+ Details

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- Definition

Initial vesting percentage after an employee completes two years of service.

+ References

No definition available.

+ Details

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- Definition

Number of days employees are prohibited from trading out of the fund to which the transfer was made.

+ References

No definition available.

+ Details

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- Definition

Vesting percentage after an employee serves five years.

+ References

No definition available.

+ Details

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- Definition

Number of years an employee serves before full vesting in the plan.

+ References

No definition available.

+ Details

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- Definition

Contribution to an individual retirement account as a percentage of employee's eligible compensation.

+ References

No definition available.

+ Details

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- Definition

Amount of cost for defined contribution plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 70
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942

+ Details

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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.

+ Details

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- Definition

Amount of discretionary contributions made by an employer to a defined contribution plan.

+ References

No definition available.

+ Details

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