LONG-TERM DEBT LONG-TERM DEBT (Tables)

12 Months Ended

Dec. 31, 2016

Long-term Debt, Unclassified [Abstract]

Schedule of Long-term Debt Instruments [Table Text Block]

Long-term debt consists of the following:

	As of December 31,
	2016			2015
	(in thousands)
Senior notes:
1.125% Convertible Notes due 2021:
Principal amount	$	200,000		$	—
Unamortized discount	(37,475		)	—
Unamortized debt issuance costs	(4,584		)	—
1.125% Convertible Notes due 2021, net of unamortized discount and debt issuance costs	157,941			—
6.125% Senior Notes due 2024:
Principal amount	400,000			—
Unamortized debt issuance costs	(7,544		)	—
6.125% Senior Notes due 2024, net of unamortized debt issuance costs	392,456			—
7.75% Senior notes due 2022:
Principal amount	500,000			500,000
Unamortized debt issuance costs	(6,443		)	(7,563		)
7.75% Senior notes due 2022, net of unamortized debt issuance costs	493,557			492,437
3.25% Convertible senior notes due 2016:
Principal amount	—			115,000
Unamortized discount	—			(1,852		)
Unamortized debt issuance costs	—			(208		)
3.25% Convertible senior notes due 2016, net of unamortized discount and debt issuance costs	—			112,940
Total senior notes	1,043,954			605,377
Revolving credit facility	—			37,000
Total debt, net of unamortized discount and debt issuance costs	1,043,954			642,377
Less current portion of long-term debt	—			112,940
Long-term debt	$	1,043,954		$	529,437