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) - USD ($)	Apr. 04, 2016	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Estimated fair value of convertible notes		$ 263,300,000	$ 262,700,000
Convertible senior notes
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)	9.25926
Conversion price (in usd per share)	$ 108.00
Share Price		$ 37.99
Closing price of stock, trigger price (in usd per share)	150.00%
Number of threshold trading days	20
Consecutive trading days	30
Effective interest rate		9.75%
Debt related commitment fees and issuance costs	$ 6,800,000
Transaction costs attributable to the liability component	4,800,000	$ 20,510,000	$ 35,131,000
Equity component of convertible debt	2,000,000.0
Convertible senior notes \| 2019 Credit Agreement
Debt Instrument [Line Items]
Aggregate principal amount of convertible senior notes	$ 250,000,000.0