Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=114867106&loc=d3e637-108580

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14A
-URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669686-108580

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=114867106&loc=d3e681-108580

THE COMPANY AND SIGNIFICANT ACCOUNTING POLICIES - New accounting pronouncements (Details) kr in Millions, $ in Millions			3 Months Ended			6 Months Ended	9 Months Ended
	Mar. 28, 2017 SEK (kr)	Mar. 28, 2017 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Jan. 01, 2019 USD ($)	Mar. 31, 2018 USD ($)	Jan. 01, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Increase to accumulated deficit										$ 31.8
Other general and administrative			$ 48.4	$ 32.6			$ 135.6	$ 113.0
Other expense (income)			(54.1)	0.4			(57.5)	1.9
Cash and restricted cash
Net cash used in operating activities							298.8	229.6
Effect of exchange rate changes on cash and cash equivalents and restricted cash							(3.2)	19.9
Cash and cash equivalents			333.3				333.3					$ 310.0
Restricted Cash and Cash Equivalents			11.0				11.0					8.3
Total cash, cash equivalents, and restricted cash shown in the consolidated statements of cash flows			344.3	291.4			344.3	291.4				318.3	$ 230.2
Accumulated other comprehensive income (loss)			$ 26.0				$ 26.0					$ 125.6
Accounting Standards Update 2017-07 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Other general and administrative				$ (0.3)				(0.6)
Other expense (income)					$ 0.3	$ 0.3
Other income					$ 0.6	$ 0.6
Accounting Standards Update 2018-02 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Increase to accumulated deficit											$ 5.0
Accounting Standards Update 2016-01 [Member]
Cash and restricted cash
Accumulated other comprehensive income (loss)											$ 0.6
Forecast \| Minimum
Leases
Lease liabilities									$ 5,000.0
Forecast \| Maximum
Leases
Lease liabilities									$ 7,000.0
Nordic
Cash and restricted cash
Acquisition	kr 5,756	$ 654.9						$ 577.6