OTHER FINANCIAL INFORMATION - CONDENSED CONSOLIDATED STATEMENT OF CASH FLOWS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Information
Net cash (used) provided by operating activities	$ 224,367	$ 296,721	$ 149,122
Investing Activities:
Capital expenditures	(44,067)	(36,210)	(21,507)
Payments to Acquire Businesses, Gross	(27,597)
Payments to Acquire Businesses, Net of Cash Acquired	(27,597)	0	0
Proceeds from sale of assets	16,795	12,461	6,766
Advances to subsidiaries and other	(5,931)	(10,393)	9,446
Net cash used in investing activities	(60,800)	(34,142)	(5,295)
Financing Activities:
Other	(3,727)	(1,211)	(2,392)
Net cash provided (used) by financing activities	(109,766)	(275,094)	(141,196)
Effect of exchange rate changes on cash and cash equivalents	758	(9,095)	5,191
Net change in cash and cash equivalents	54,559	(21,610)	7,822
Cash and cash equivalents at the beginning of period	96,343	117,953	110,131
Cash and cash equivalents at the end of period	150,902	96,343	117,953
Parent Company
Condensed Financial Information
Net cash (used) provided by operating activities	20,328	18,672	(36,575)
Investing Activities:
Capital expenditures	0	0	0
Payments to Acquire Businesses, Gross	0
Proceeds from sale of assets	0	0	0
Proceeds from Dividends Received	0	0	0
Payments for Advance to Affiliate	0	0	0
Net cash used in investing activities	0	0	0
Financing Activities:
Proceeds from Issuance of Debt	132,721	108,497	143,367
Repayments of Debt	0	0	0
Equity transactions	(153,049)	(127,169)	(106,792)
SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Subsidiaries and Equity Method Investees	0	0	0
Other	0	0	0
Net cash provided (used) by financing activities	(20,328)	(18,672)	36,575
Effect of exchange rate changes on cash and cash equivalents	0	0	0
Net change in cash and cash equivalents	0	0	0
Cash and cash equivalents at the beginning of period	0	0	0
Cash and cash equivalents at the end of period	0	0	0
Guarantor Subsidiaries
Condensed Financial Information
Net cash (used) provided by operating activities	188,797	153,467	101,826
Investing Activities:
Capital expenditures	(22,330)	(17,573)	(13,215)
Payments to Acquire Businesses, Gross	(27,597)
Proceeds from sale of assets	0	0	0
Proceeds from Dividends Received	134,853	347,531	307,784
Payments for Advance to Affiliate	222,482	406,028	383,686
Net cash used in investing activities	(137,556)	(76,070)	(89,117)
Financing Activities:
Proceeds from Issuance of Debt	423,441	339,606	775,926
Repayments of Debt	(449,190)	(410,606)	(785,392)
Equity transactions	0	0	0
SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Subsidiaries and Equity Method Investees	0	0	0
Other	(14,924)	(21,068)	5,807
Net cash provided (used) by financing activities	(40,673)	(92,068)	(3,659)
Effect of exchange rate changes on cash and cash equivalents	0	0	0
Net change in cash and cash equivalents	10,568	(14,671)	9,050
Cash and cash equivalents at the beginning of period	35,931	50,602	41,552
Cash and cash equivalents at the end of period	46,499	35,931	50,602
Non-Guarantor Subsidiaries
Condensed Financial Information
Net cash (used) provided by operating activities	15,242	124,582	83,871
Investing Activities:
Capital expenditures	(21,737)	(18,637)	(8,292)
Payments to Acquire Businesses, Gross	0
Proceeds from sale of assets	16,795	12,461	6,766
Proceeds from Dividends Received	0	0	0
Payments for Advance to Affiliate	5,931	(196,219)	(26,912)
Net cash used in investing activities	(10,873)	190,043	25,386
Financing Activities:
Proceeds from Issuance of Debt	998,019	1,086,673	1,144,848
Repayments of Debt	(824,302)	(1,051,611)	(952,740)
Equity transactions	0	0	0
SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Subsidiaries and Equity Method Investees	(134,853)	(347,531)	(307,784)
Other	0	0	0
Net cash provided (used) by financing activities	38,864	(312,469)	(115,676)
Effect of exchange rate changes on cash and cash equivalents	758	(9,095)	5,191
Net change in cash and cash equivalents	43,991	(6,939)	(1,228)
Cash and cash equivalents at the beginning of period	60,412	67,351	68,579
Cash and cash equivalents at the end of period	104,403	60,412	67,351
Consolidated Entities [Member]
Condensed Financial Information
Net cash (used) provided by operating activities	224,367	296,721	149,122
Investing Activities:
Capital expenditures	(44,067)	(36,210)	(21,507)
Payments to Acquire Businesses, Gross	(27,597)
Proceeds from sale of assets	16,795	12,461	6,766
Proceeds from Dividends Received	0	0	0
Payments for Advance to Affiliate	5,931	10,393	(9,446)
Net cash used in investing activities	(60,800)	(34,142)	(5,295)
Financing Activities:
Proceeds from Issuance of Debt	1,331,699	1,335,360	1,680,455
Repayments of Debt	(1,273,492)	(1,462,217)	(1,720,666)
Equity transactions	(153,049)	(127,169)	(106,792)
SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Subsidiaries and Equity Method Investees	0	0	0
Other	(14,924)	(21,068)	5,807
Net cash provided (used) by financing activities	(109,766)	(275,094)	(141,196)
Effect of exchange rate changes on cash and cash equivalents	758	(9,095)	5,191
Net change in cash and cash equivalents	54,559	(21,610)	7,822
Cash and cash equivalents at the beginning of period	96,343	117,953	110,131
Cash and cash equivalents at the end of period	150,902	96,343	117,953
Consolidation, Eliminations [Member]
Condensed Financial Information
Net cash (used) provided by operating activities	0	0	0
Investing Activities:
Capital expenditures	0	0	0
Payments to Acquire Businesses, Gross	0
Proceeds from sale of assets	0	0	0
Proceeds from Dividends Received	(134,853)	(347,531)	(307,784)
Payments for Advance to Affiliate	(222,482)	(199,416)	(366,220)
Net cash used in investing activities	87,629	(148,115)	58,436
Financing Activities:
Proceeds from Issuance of Debt	(222,482)	(199,416)	(383,686)
Repayments of Debt	0	0	17,466
Equity transactions	0	0	0
SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Subsidiaries and Equity Method Investees	134,853	347,531	307,784
Other	0	0	0
Net cash provided (used) by financing activities	(87,629)	148,115	(58,436)
Effect of exchange rate changes on cash and cash equivalents	0	0	0
Net change in cash and cash equivalents	0	0	0
Cash and cash equivalents at the beginning of period	0	0	0
Cash and cash equivalents at the end of period	$ 0	$ 0	$ 0