CREDIT FACILITY AND LONG-TERM DEBT (Summary of Long-Term Debt) (Details) - USD ($)		Dec. 31, 2017		Dec. 31, 2016	Nov. 24, 2015	Feb. 09, 2012
Debt Instrument [Line Items]
Long-term Debt		$ 1,662,414,000
Unamortized deferred financing costs		25,178,000		$ 25,277,000
Debt, Long-term and Short-term, Combined Amount		1,637,236,000		1,576,559,000
Less—Current debt		(10,987,000)		0
Long-term Debt and Capital Lease Obligations		1,626,249,000		1,576,559,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Long-term Line of Credit	[1]			350,000,000
2025 Senior Notes [Member]
Debt Instrument [Line Items]
Long-term Debt	[2]	725,000,000		0
Senior Secured Notes [Member]
Debt Instrument [Line Items]
Long-term Debt	[2]	$ 0		670,867,000
Annual interest rate		8.25%				8.25%
2023 Senior Notes [Member]
Debt Instrument [Line Items]
Long-term Debt	[2],[3]	$ 500,000,000		500,000,000
Annual interest rate					7.00%
Line of Credit [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Long-term Line of Credit		350,000,000	[1]	350,000,000
Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 28,366,000		35,000,000
Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Long-term Debt				$ 45,969,000

[1] (b) The estimated fair value approximates carrying value, categorized as a Level 2 measurement, as these borrowings bear interest based upon short-term floating market interest rates.

[2] (a) The estimated fair value, categorized as a Level 2 measurement, was calculated based on the present value of future expected payments utilizing implied current market interest rates based on quoted prices of the Senior Notes and Senior Secured Notes.

[3] (d) As discussed in “Note 8 - Credit Facility and Debt”, these notes became unsecured following the Collateral Fall-Away Event on May 30, 2017.