Long Term Debt and Financing Arrangements - Narrative (Details) - USD ($)	1 Months Ended		3 Months Ended
	Feb. 28, 2018	Jan. 31, 2018	Mar. 31, 2018	Mar. 31, 2017	Feb. 02, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term debt borrowings			$ 947,500,000	$ 0
Short-term debt and current portion of long-term debt			$ 177,500,000			$ 68,100,000
Senior Notes | Notes 2028 Term
Debt Instrument [Line Items]
Face amount	$ 450,000,000				$ 450,000,000
Interest rate, stated percentage	3.50%		3.50%		3.50%
Long-term debt borrowings	$ 442,600,000
Line of Credit | Term Loan Agreement
Debt Instrument [Line Items]
Line of credit, maximum borrowing capacity		$ 500,000,000			$ 500,000,000
Amortization percentage, equal quarterly installments, year one					5.00%
Amortization percentage, equal quarterly installments, year two					5.00%
Amortization percentage, equal quarterly installments, year three					7.50%
Amortization percentage, equal quarterly installments, year four					10.00%
Amortization percentage, equal quarterly installments, year five					10.00%
Revolving Credit Facility | Line of Credit | Credit Agreement
Debt Instrument [Line Items]
Line of credit, maximum borrowing capacity		$ 750,000,000
Line of credit facility covenants maximum debt to capitalization percentage		65.00%
Debt term		5 years
Line of credit facility, accordion feature, higher borrowing capacity option		$ 1,250,000,000.000