WISCONSIN ECONOMIC DEVELOPMENT TAX CREDIT (Details) - Wisconsin Economic Development Tax Credit Agreement $ in Millions	3 Months Ended			6 Months Ended		30 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2015 USD ($) item	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)
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						$ 5.9
Refundable tax credit received						1.1
Refundable tax credit receivable	$ 4.8			$ 4.8		4.8
Amortization of tax credits	0.3	$ 0.2		0.6	$ 0.3
Prepaid expenses and other current assets
Agreements
Refundable tax credit receivable	1.3			1.3		1.3
Other long-term assets
Agreements
Refundable tax credit receivable	3.5			3.5		3.5
Short-term other liabilities
Agreements
Refundable tax credit, offsetting liability	1.3			1.3		1.3
Other long-term liabilities
Agreements
Refundable tax credit, offsetting liability	$ 3.1			$ 3.1		$ 3.1