Employee Benefit Plans US Changes in Assets measured at fair value using significant unobservable inputs (Details) - Fair Value, Inputs, Level 3 - Pension Benefits, U.S. Plans - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Beginning Balance of Assets Measured with Unobservable Inputs	$ 122.1	$ 103.7
Actual Return on Plan Assets Still Held	7.8	9.7
Actual Return on Plan Assets Sold During Period	1.6	2.6
Purchases	14.5	38.8
Sales	(9.4)	(32.7)
Level 3 Transfers Into	0.0	0.0
Level 3 Transfers Out of	0.0	0.0
Ending Balance of Assets Measured with Unobservable Inputs	136.6	122.1
Private Equity Direct Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Beginning Balance of Assets Measured with Unobservable Inputs	17.2	7.2
Actual Return on Plan Assets Still Held	4.2	1.7
Actual Return on Plan Assets Sold During Period	(0.2)	0.1
Purchases	11.9	9.0
Sales	(2.7)	(0.8)
Level 3 Transfers Into	0.0	0.0
Level 3 Transfers Out of	0.0	0.0
Ending Balance of Assets Measured with Unobservable Inputs	30.4	17.2
Private Equity Funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Beginning Balance of Assets Measured with Unobservable Inputs	34.9	29.6
Actual Return on Plan Assets Still Held	2.5	4.8
Actual Return on Plan Assets Sold During Period	2.0	2.6
Purchases	2.4	3.9
Sales	(6.5)	(6.0)
Level 3 Transfers Into	0.0	0.0
Level 3 Transfers Out of	0.0	0.0
Ending Balance of Assets Measured with Unobservable Inputs	35.3	34.9
Hedge Funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Beginning Balance of Assets Measured with Unobservable Inputs	70.0	66.9
Actual Return on Plan Assets Still Held	1.1	3.2
Actual Return on Plan Assets Sold During Period	(0.2)	(0.1)
Purchases	0.2	25.9
Sales	(0.2)	(25.9)
Level 3 Transfers Into	0.0	0.0
Level 3 Transfers Out of	0.0	0.0
Ending Balance of Assets Measured with Unobservable Inputs	$ 70.9	$ 70.0