GOODWILL AND OTHER INTANGIBLE ASSETS - Intangible assets (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Intangible assets
Amortizing intangibles	$ 66,949	$ 71,350
Accumulated amortization	(49,128)	(38,311)
Amortizing intangibles, net	17,821	33,039
Non-amortizing intangibles	1,034,284	1,012,839
Intangibles, net	1,052,105	1,045,878
Amortization expense	$ 11,600	$ 11,900	$ 11,900
Minimum
Intangible assets
Useful life of intangible assets	5 years
Maximum
Intangible assets
Useful life of intangible assets	7 years

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

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-Publisher FASB
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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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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 after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit.

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Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

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