New Accounting Standards (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax expense (benefit)	$ 41,400,000	$ 80,900,000	$ 54,400,000
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	4,100,000	7,300,000
Defined Benefit Plan, Service Cost	10,800,000	10,400,000
Restricted cash		0		$ 0
Operating leases, future minimum payments due	81,500,000
Accounting Standards Update 2016-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax expense (benefit)	14,300,000	33,100,000
Accounting Standards Update 2017-07 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Defined Benefit Plan, Other Cost (Credit)	6,700,000	3,100,000
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating leases, future minimum payments due	$ 81,500,000	$ 79,100,000