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Accounting Policies (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended			0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 01, 2014
Gross Balance
Balance at the beginning of the period	$ 539.3us-gaap_GoodwillGross	$ 528.2us-gaap_GoodwillGross
Acquired During the Period	174.3us-gaap_GoodwillAcquiredDuringPeriod
Foreign Currency Translation and Other	(37.2)	11.1
Balance at the end of the period	676.4us-gaap_GoodwillGross	539.3us-gaap_GoodwillGross
Accumulated Impairment Losses
Balance at the beginning of the period	(24.5)	(24.2)
Impairment Loss During the Period	(12.9)	(0.3)
Balance at the end of the period	(37.4)	(24.5)
Net Goodwill	639.0us-gaap_Goodwill	514.8us-gaap_Goodwill
Business combination
Purchase price allocated to goodwill	639.0us-gaap_Goodwill	514.8us-gaap_Goodwill
Tax benefit on Impairment charge	0wts_TaxBenefitOnImpairmentCharge
BRAE
Accumulated Impairment Losses
Earnout liability		0
Business combination
Goodwill Impairment Charge		0.3	1.0
Aerco
Accumulated Impairment Losses
Net Goodwill				174.3
Business combination
Aggregate consideration, net				272.2
Purchase price allocated to goodwill				174.3
Purchase price allocated to intangible assets				102.4
Americas
Gross Balance
Balance at the beginning of the period	224.7	225.6
Acquired During the Period	174.3
Foreign Currency Translation and Other	(1.0)	(0.9)
Balance at the end of the period	398.0	224.7
Accumulated Impairment Losses
Balance at the beginning of the period	(24.5)	(24.2)
Impairment Loss During the Period		(0.3)
Balance at the end of the period	(24.5)	(24.5)
Net Goodwill	373.5	200.2
Business combination
Purchase price allocated to goodwill	373.5	200.2
EMEA
Gross Balance
Balance at the beginning of the period	301.3	289.7
Foreign Currency Translation and Other	(35.8)	11.6
Balance at the end of the period	265.5	301.3
Accumulated Impairment Losses
Net Goodwill	265.5	301.3
Business combination
Purchase price allocated to goodwill	265.5	301.3
Asia Pacific
Gross Balance
Balance at the beginning of the period	13.3	12.9
Foreign Currency Translation and Other	(0.4)	0.4
Balance at the end of the period	12.9	13.3
Accumulated Impairment Losses
Impairment Loss During the Period	(12.9)
Balance at the end of the period	(12.9)
Net Goodwill		13.3
Business combination
Purchase price allocated to goodwill		$ 13.3