Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Aug. 31, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Life (in Years)				13 years 2 months 30 days		13 years 6 months 40 days
Gross Carrying Amount		$ 435.1		$ 435.1		$ 333.5
Accumulated Amortization		80.3		80.3		$ 62.7
Intangible assets amortization expense		6.3	$ 5.7	$ 17.5	$ 17.1
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Life (in Years)				13 years 3 months 30 days		13 years 4 months
Gross Carrying Amount		408.0		$ 408.0		$ 311.5
Accumulated Amortization		73.2		$ 73.2		$ 57.3
Trademarks and Trade Names
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Life (in Years)				11 years 8 months		13 years 6 months 33 days
Gross Carrying Amount		25.6		$ 25.6		$ 21.8
Accumulated Amortization		6.9		$ 6.9		$ 5.2
Other Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Life (in Years)				2 years 10 months 30 days		1 year 2 months 12 days
Gross Carrying Amount		1.5		$ 1.5		$ 0.2
Accumulated Amortization		$ 0.2		$ 0.2		$ 0.2
TimBar Corporation | Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired	$ 96.5
TimBar Corporation | Trademarks and Trade Names
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired	3.8
TimBar Corporation | Other Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired	$ 1.3