Redeemable Noncontrolling Interest (Details) $ in Millions		3 Months Ended		9 Months Ended			12 Months Ended
		Sep. 30, 2017 USD ($) shares	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) shares		Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)	Apr. 01, 2021 installment	Apr. 01, 2018 installment	Apr. 01, 2015 installment
Redeemable Noncontrolling Interest [Line Items]
Number of Installments Related to Stockholders Agreement | installment										2
Increase (Decrease) in Temporary Equity [Roll Forward]
Balance, Beginning of period				$ 483.7	[1]	$ 464.9	$ 464.9
Net income attributable to NCI		$ (9.2)	$ 6.8	1.9		11.3	26.2
Other comprehensive income (loss) attributable to NCI		0.7	(1.2)	2.9		2.3	(3.2)
Exercise of employee stock options				3.4		0.0	0.0
Change in redemption value of NCI				6.3		(6.0)	(4.2)
Balance, End of period	[1]	$ 498.2	$ 472.5	$ 498.2		$ 472.5	$ 483.7
ARX Holding Corp. [Member]
Redeemable Noncontrolling Interest [Line Items]
Business Combination, Step Acquisition, Equity Interest in Acquiree, Including Subsequent Acquisition, Percentage		69.00%	69.20%	69.00%		69.20%	69.20%
Shares held in Employee Stock Option Plan, Suspense Shares | shares		22,550		22,550
Employee Stock Ownership Plan (ESOP), Deferred Shares, Fair Value		$ 32.2		$ 32.2
Scenario, Forecast [Member]
Redeemable Noncontrolling Interest [Line Items]
Number of Installments Related to Stockholders Agreement | installment								1	1
Scenario, Forecast [Member] | ARX Holding Corp. [Member]
Redeemable Noncontrolling Interest [Line Items]
Business Combination, Step Acquisition, Equity Interest in Acquiree, Including Subsequent Acquisition, Percentage								100.00%	80.00%

[1] See Note 12 – Redeemable Noncontrolling Interest for further discussion.