DEBT Additional Information (Detail)			3 Months Ended		9 Months Ended
	Apr. 04, 2017 USD ($)	Jul. 21, 2014 USD ($) $ / shares $ / unit shares	Sep. 30, 2017 USD ($) $ / shares	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) d $ / shares	Sep. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Aug. 15, 2014 USD ($)
Debt Instrument [Line Items]
Total debt			$ 282,813,000		$ 282,813,000
Non-cash interest expense					5,356,000	$ 4,700,000
Write-off of deferred financing costs	$ 300,000				0	340,000
Convertible Senior 2019 Notes [Member] | Convertible Debt [Member]
Debt Instrument [Line Items]
Initial issued principal amount		$ 130,000,000						$ 19,500,000
Total debt		$ 149,500,000	$ 149,500,000		$ 149,500,000
Interest rate per annum		2.50%
Threshold Trading Days (Whether or Not Consecutive) | d					20
Threshold Consecutive Trading Days | d					30
Threshold Percentage of Stock Price Trigger					130.00%
Principal Amount of Convertible Notes		$ 1,000
Maximum Percent of Conversion Rate for Each Trading Day		98.00%
Initial conversion rate | shares		67.41
Initial conversion price | $ / shares		$ 14.83	$ 14.83		$ 14.83
Repurchase price percentage of principal					100.00%
Long-term Debt			$ 137,300,000		$ 137,300,000
Debt discount			10,500,000		10,500,000
Unamortized deferred financing costs			1,700,000		1,700,000
Fair value of liability component of Notes			139,400,000		139,400,000
Interest expense recognized on debt agreement			2,600,000	$ 2,500,000	7,700,000	7,500,000
Non-cash interest expense			1,400,000	1,300,000	4,200,000	4,000,000
Amortization of Financing Costs			$ 200,000	$ 200,000	$ 700,000	$ 700,000
Payments for Hedging Activities		$ 18,400,000
Derivative, Cap Price | $ / unit		19.38
The Revolver [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity, revolving credit facility							$ 20,000,000
The Revolver [Member] | Revolving Credit Facility [Member] | Swing Line [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity, revolving credit facility		$ 10,000,000
The Revolver [Member] | Revolving Credit Facility [Member] | Letter of Credit [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity, revolving credit facility		$ 15,000,000