Debt and Credit Agreements (Details)			1 Months Ended	12 Months Ended
	Dec. 02, 2015 USD ($)	Sep. 12, 2013	Mar. 31, 2012 USD ($) bank	Dec. 31, 2015 USD ($)	Dec. 01, 2015 USD ($)	Dec. 31, 2014 USD ($)
Line of Credit Facility [Line Items]
Long-term debt				$ 880,835,000		$ 854,897,000
Short-term borrowings				30,229,000		16,748,000
Current maturities of long-term debt				$ 25,084,000		$ 25,188,000
Minimum consolidated interest coverage ratio, numerator				3
Minimum consolidated interest coverage ratio, denominator				1
Weighted average interest rate				4.30%		11.70%
Secured Debt | Senior Secured Credit Facilities
Line of Credit Facility [Line Items]
Long-term debt				$ 380,500,000
Long-term and Short-term, combined amount				415,000,000
Short-term borrowings				22,000,000
Current maturities of long-term debt				$ 12,500,000
Term Loan | Term Loan Facility 2015
Line of Credit Facility [Line Items]
Principle amount	$ 250,000,000
Periodic payment, percentage of principle for payments made in 2016				1.25%
Periodic payment, percentage of principle for payments after 2016				2.50%
Long-term debt				$ 250,000,000		$ 0
Minimum consolidated interest coverage ratio, numerator		3.0
Credit Agreement
Line of Credit Facility [Line Items]
Facility Limit	$ 600,000,000		$ 525,000,000	350,000,000	$ 500,000,000
Outstanding Balance				165,000,000		98,500,000
Letters of Credit Outstanding, Amount				44,400,000
Available Credit				140,600,000
Number of lenders providing credit facility | bank			14
Debt Issuance Cost				600,000
Minimum consolidated interest coverage ratio, numerator		4.0
Minimum consolidated interest coverage ratio, denominator		1
Revolving Credit Facility
Line of Credit Facility [Line Items]
Long-term debt				143,000,000		$ 0
Long-term and Short-term, combined amount				165,000,000
Short-term borrowings				$ 22,000,000.0
Minimum | Base Rate | Secured Debt | Senior Secured Credit Facilities
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.875%
Minimum | LIBOR | Secured Debt | Senior Secured Credit Facilities
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.875%
Maximum | Base Rate | Secured Debt | Senior Secured Credit Facilities
Line of Credit Facility [Line Items]
Basis spread on variable rate	2.00%
Maximum | LIBOR | Secured Debt | Senior Secured Credit Facilities
Line of Credit Facility [Line Items]
Basis spread on variable rate	3.00%