Employee Benefit Plans and Other Postretirement Plans - Change in Benefit Obligations and Change in Fair Value of Plan Assets Related to Pension and Postretirement Plans (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value at beginning of period		$ 805.9
Company contributions			$ 0.4	$ 30.0
Fair value of plan assets at plan year end		764.4	805.9
Amounts Recognized on Consolidated Balance Sheets
Noncurrent liabilities		(358.6)	$ (361.7)
Amounts Recognized in Accumulated Other Comprehensive (Income) Loss (Pre-Tax)
Accumulated benefit obligation for plans with obligations in excess of plan assets		$ 1,050.0
Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Weighted-Average Assumptions Used to Determine Benefit Obligation, Discount Rate		4.51%	4.14%	5.00%
Change in Benefit Obligations [Roll Forward]
Benefit obligation at beginning of period		$ 1,129.6	$ 929.8
Service cost		24.0	22.7	$ 24.5
Interest cost		46.2	45.9	21.5
Plan amendments		3.0	2.6
Actuarial (gain) loss	[1]	(75.7)	159.2
Special termination benefits		0.0	0.3	0.0
Participant contributions		0.0	0.0
Benefits paid		(34.6)	(30.9)
Benefit obligation at plan year end		1,092.5	1,129.6	929.8
Accumulated benefit obligation portion of above		1,048.5	1,078.6
Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value at beginning of period		805.9	772.1
Actual return on plan assets		(8.1)	63.4
Company contributions		1.2	1.3
Participant contributions		0.0	0.0
Benefits paid		(34.6)	(30.9)
Fair value of plan assets at plan year end		764.4	805.9	$ 772.1
Underfunded status		(328.1)	(323.7)
Amounts Recognized on Consolidated Balance Sheets
Current liabilities		(0.9)	(1.1)
Noncurrent liabilities		(327.2)	(322.6)
Accrued obligation recognized at December 31		(328.1)	(323.7)
Amounts Recognized in Accumulated Other Comprehensive (Income) Loss (Pre-Tax)
Amounts Recognized in Accumulated Other Comprehensive (Income) Loss (Pre-Tax)		25.1	27.6
Actuarial loss		149.4	172.6
Total		$ 174.5	$ 200.2
Postretirement Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Weighted-Average Assumptions Used to Determine Benefit Obligation, Discount Rate		4.35%	3.95%	4.85%
Change in Benefit Obligations [Roll Forward]
Benefit obligation at beginning of period		$ 31.9	$ 26.3
Service cost		1.7	1.6	$ 2.1
Interest cost		1.2	1.2	1.3
Plan amendments		0.0	0.0
Actuarial (gain) loss		(11.4)	4.1
Special termination benefits		0.0	0.0	0.0
Participant contributions		1.2	1.2
Benefits paid		(3.2)	(2.5)
Benefit obligation at plan year end		21.4	31.9	26.3
Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value at beginning of period		0.0	0.0
Actual return on plan assets		0.0	0.0
Company contributions		2.0	1.3
Participant contributions		1.2	1.2
Benefits paid		(3.2)	(2.5)
Fair value of plan assets at plan year end		0.0	0.0	$ 0.0
Underfunded status		(21.4)	(31.9)
Amounts Recognized on Consolidated Balance Sheets
Current liabilities		(1.1)	(1.4)
Noncurrent liabilities		(20.3)	(30.5)
Accrued obligation recognized at December 31		(21.4)	(31.9)
Amounts Recognized in Accumulated Other Comprehensive (Income) Loss (Pre-Tax)
Amounts Recognized in Accumulated Other Comprehensive (Income) Loss (Pre-Tax)		0.2	0.3
Actuarial loss		(6.0)	5.5
Total		$ (5.8)	$ 5.8

[1] In 2015, the increase in the weighted average discount rate used to estimate our pension benefit obligations and changes in mortality assumptions from the Society of Actuaries resulted in an actuarial gain. The actuarial loss in 2014 was due primarily to a decrease in the weighted average discount rate and updated mortality assumptions.