Employee Benefit Plans - Accumulated Other Comprehensive Loss (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($)
U.S. Qualified Plans
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax [Abstract]
Actuarial gain (loss)	$ (22.2)
Net periodic benefit expense (income):
Interest cost	12.7
Expected return on plan assets	(15.4)
Net periodic benefit expense (income)	(2.7)
Amounts recognized in other comprehensive income or loss:
Actuarial loss (gain)	22.2
Loss (gain) recognized in other comprehensive income or loss	$ 22.2
Defined Benefit Plan, Assumptions Used in Calculations [Abstract]
Discount rate	4.55%
Expected long-term rate of return on plan assets	5.57%
U.S Non-Qualified Plans
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax [Abstract]
Actuarial gain (loss)	$ 0.7
Net periodic benefit expense (income):
Interest cost	0.5
Expected return on plan assets	0.0
Net periodic benefit expense (income)	0.5
Amounts recognized in other comprehensive income or loss:
Actuarial loss (gain)	(0.7)
Loss (gain) recognized in other comprehensive income or loss	(0.7)
UK Plans
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax [Abstract]
Actuarial gain (loss)	0.5
Net periodic benefit expense (income):
Interest cost	28.6
Expected return on plan assets	(34.6)
Net periodic benefit expense (income)	(6.0)
Amounts recognized in other comprehensive income or loss:
Actuarial loss (gain)	(0.5)
Loss (gain) recognized in other comprehensive income or loss	$ (0.5)
Defined Benefit Plan, Assumptions Used in Calculations [Abstract]
Discount rate	3.75%
Expected long-term rate of return on plan assets	5.40%
Postretirement Medical Plan
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax [Abstract]
Actuarial gain (loss)	$ (3.3)
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	(3.3)
Net periodic benefit expense (income):
Service cost - benefits earned during the year	0.1
Interest cost	0.3
Net periodic benefit expense (income)	$ 0.4
Defined Benefit Plan, Assumptions Used in Calculations [Abstract]
Discount rate	4.10%