Adjustment to additional paid in capital resulting from the recognition of convertible debt instruments as two separate components - a debt component and an equity component. This bifurcation may result in a basis difference associated with the liability component that represents a temporary difference for purposes of applying accounting for income taxes. The initial recognition of deferred taxes for the tax effect of that temporary difference is as an adjustment to additional paid in capital.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 25
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=51819886&loc=SL6014347-161799

FINANCING ARRANGEMENTS - Convertible Senior Notes (Details)		1 Months Ended	3 Months Ended	12 Months Ended
	Apr. 04, 2016 USD ($) $ / shares shares	Apr. 20, 2020 number_of_day	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2018 USD ($) $ / shares
Debt Instrument [Line Items]
Net proceeds				$ 243,200,000
Stated interest rate	3.25%
Principal amount converted initially	$ 1,000
Number of shares converted (in shares) \| shares	185.1852
Conversion price (in usd per share) \| $ / shares	$ 5.40
Common stock, par value (in usd per share) \| $ / shares						$ 3.20
Closing price of stock, trigger price (in usd per share)	150.00%
Effective interest rate				9.75%
Debt related commitment fees and issuance costs				$ 6,800,000
Debt issuance costs				4,800,000
Equity component of convertible debt			$ 2,000,000		$ 67,014,000
Estimated fair value of convertible notes				$ 285,600,000		$ 257,100,000
Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount of convertible senior notes	$ 250,000,000
Subsequent Event
Debt Instrument [Line Items]
Number of threshold trading days		20
Consecutive trading days \| number_of_day		30