Employee Benefits (Details) employee in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) employee	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Number of Fixed Income Funds Investing in Debt Securities Ecured by Royalty Payments [Line Items]
Number of employees sponsored by defined benefit pension plans | employee	9
Profit Sharing Bonus	$ 0	$ 5,500,000	$ 0
Employer discretionary contribution amount	7,200,000	4,700,000	2,100,000
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	1,202,700,000	1,355,200,000
Service cost	6,500,000	4,600,000	4,300,000
Interest cost	55,900,000	57,200,000	60,700,000
Benefits paid	(79,100,000)	(151,900,000)
Actuarial loss	53,400,000	(60,200,000)
Expenses paid from assets	(5,900,000)	(5,800,000)
Other	100,000	3,600,000
Benefit obligation at year end	1,233,600,000	1,202,700,000	1,355,200,000
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets beginning of year	867,100,000	899,300,000
Actual return on plan assets	39,900,000	56,600,000
Employer contributions	56,500,000	70,900,000
Benefits paid	(79,100,000)	(151,900,000)
Expenses paid from assets	(5,900,000)	(5,800,000)
Other	200,000	(2,000,000)
Fair value of plan assets at year end	878,700,000	867,100,000	899,300,000
Funded status at year end	(354,900,000)	(335,600,000)
Settlements, plan assets	85,200,000
Noncurrent assets	1,200,000	1,300,000
Current liabilities	700,000	700,000
Noncurrent liabilities	355,400,000	336,200,000
Net actuarial loss	462,100,000	406,000,000
Unrecognized actuarial losses net of tax	424,100,000
Actuarial loss included in accumulated other comprehensive income and expected to be recognized next year	15,700,000
Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Accumulated Benefit Obligation	1,233,200,000	1,202,200,000
Pension Settlement Charge	$ 0	$ 28,700,000	$ 0