WISCONSIN ECONOMIC DEVELOPMENT TAX CREDIT (Details) - Wisconsin Economic Development Tax Credit Agreement $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2015 USD ($) item	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)
Agreements
Refundable tax credits available, contingent on the Company expending $26.3 million in capital investments and establishing 758 full-time positions			$ 9.0
Capital investment expenditures over specified period, requirement to earn the refundable tax credits			$ 26.3
Full-time positions that must be created over a specified time period to earn the refundable tax credits | item			758
Period over which the capital investment expenditures must be incurred and the creation of full-time positions must be completed			7 years
Refundable tax credits earned				$ 9.0
Refundable tax credit received				4.3
Refundable tax credit receivable	$ 4.7			4.7
Amortization of tax credits	0.6	$ 0.4		1.2	$ 1.0
Prepaid expenses and other current assets
Agreements
Refundable tax credit receivable	1.6			1.6
Other long-term assets
Agreements
Refundable tax credit receivable	3.1			3.1
Short-term other liabilities
Agreements
Refundable tax credit, offsetting liability	2.4			2.4
Other long-term liabilities
Agreements
Refundable tax credit, offsetting liability	$ 1.0			$ 1.0