Goodwill And Intangible Assets (Summary Of Intangible Assets) (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016	Dec. 31, 2015
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year	$ 15.6
Finite-Lived Intangible Assets, Amortization Expense, Year Two	28.5
Finite-Lived Intangible Assets, Amortization Expense, Year Three	$ 26.1
Weighted Average Amortization Period of Finite Lived Assets (in years)	15 years 10 months 24 days
Gross Asset	$ 575.8	$ 546.7
Accumulated Amortization	282.7	264.5
Net	293.1	282.2
Finite-Lived Intangible Assets, Net	293.1	282.2	$ 317.1
Finite-Lived Intangible Assets, Amortization Expense, Year Four	22.1
Finite-Lived Intangible Assets, Amortization Expense, Year Five	$ 172.8
Intellectual Property Rights
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period of Finite Lived Assets (in years)	16 years 6 months 24 days
Gross Asset	$ 89.3	86.4
Accumulated Amortization	52.3	52.1
Net	$ 37.0	34.3
Customer Relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period of Finite Lived Assets (in years)	15 years 8 months 12 days
Gross Asset	$ 414.2	388.9
Accumulated Amortization	168.6	153.4
Net	$ 245.6	235.5
Drawings
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period of Finite Lived Assets (in years)	37 years 10 months 24 days
Gross Asset	$ 11.1	11.1
Accumulated Amortization	10.3	10.3
Net	$ 0.8	0.8
Other Intangible Assets
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period of Finite Lived Assets (in years)	13 years
Gross Asset	$ 61.2	60.3
Accumulated Amortization	51.5	48.7
Net	$ 9.7	$ 11.6