EQUITY INVESTMENTS - Income From Equity Method Investments (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Equity Method Investments and Joint Ventures [Abstract]
Representation of investee financial information in the summarized equity method investments (as a percent)			100.00%
INCOME STATEMENT DATA:
Revenue	$ 145,622	$ 133,355	$ 290,690	$ 260,039
Operating income	40,027	39,784	89,809	85,429
Net income	26,382	23,821	51,132	53,933
Net income attributable to investee	$ 25,170	$ 15,795	$ 48,129	$ 39,782

Equity Method Investment, Summarized Financial Information, Net Income (Loss) Attributable To Equity Method Investee

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- Definition

Represents the percentage of investee financial information in the summarized equity method investments.

+ References

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Amount of income (loss) from continuing operations reported by an equity method investee.

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The amount of net income (loss) reported by an equity method investment of the entity.

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The amount of revenue from sale of goods and services reduced by sales returns, allowances, and discounts reported by an equity method investment of the entity.

+ References

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