Long-Term Debt (Details)		3 Months Ended	12 Months Ended			36 Months Ended	60 Months Ended		120 Months Ended
	Sep. 30, 2015 USD ($)	Mar. 31, 2011 USD ($)	Dec. 31, 2015 USD ($) Installments	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Jun. 01, 2014	Jun. 01, 2021	Jun. 01, 2016	Jun. 02, 2021	Apr. 21, 2015 USD ($)	Jun. 30, 2014 USD ($)	May. 21, 2011 USD ($)	Apr. 30, 2010	Apr. 30, 1998 USD ($)
Debt Instrument [Line Items]
Potential Increase to Term Loan and Line of Credit	$ 750,000,000
Accrued Interest Expense Debt			$ 3,600,000	$ 9,200,000
Senior Debentures													0.500
Long-term debt			1,364,008,000	1,330,563,000
Debt Issuance Cost			6,500,000
Interest expense			65,311,000	71,092,000	$ 52,350,000
Payments of Debt Issuance Costs			6,452,000	14,042,000	10,436,000
Deferred Costs, Current										$ 14,800,000
Write off of Deferred Debt Issuance Cost			$ 1,600,000
Interest Rate Swap realized Gain Loss			4,100,000
Market value adjustments on interest rate swap, net of tax			$ (364,000)	$ (2,408,000)	1,526,000
7.25% senior notes due June 2021 [Member]
Debt Instrument [Line Items]
Debt instrument, aggregate principal amount												$ 400,000,000
Stated rate on debt												7.25%
Contingent Credit Agreement Term Loan Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	850,000,000
Contingent Credit Agreement Revolving Facility [Domain]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	550,000,000
Multi Currency Sub Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	100,000,000
Letter Of Credit Sub Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	50,000,000
Credit Agreement [Member]
Debt Instrument [Line Items]
Line Of Credit Facility, Threshold of Fair Market Value Of Assets and Properties as Collateral			$ 10,000,000
7.55% senior debentures due April 2028 [Member]
Debt Instrument [Line Items]
Debt instrument, aggregate principal amount														$ 100,000,000
Notes Payable to Banks [Member] | 7.25% senior notes due June 2021 [Member]
Debt Instrument [Line Items]
Stated rate on debt			7.25%
Debt Instrument, Redemption Price, Percentage Of Aggregate Principle Amount						107.25%
Percentage Of Original Principle Amount Redeemable						35.00%
Debt Instrument, Debt Restrictive Covenants, Interest Coverage Ratio				2.00
Long-term debt			$ 393,000,000	$ 393,000,000
Notes Payable to Banks [Member] | 7.55% senior debentures due April 2028 [Member]
Debt Instrument [Line Items]
Stated rate on debt			7.55%											7.55%
Long-term debt			$ 59,645,000	59,645,000
Line of Credit [Member] | Revolving line of credit borrowings due May 2016, weighted-average interest rate of 1.9% at December 31, 2013, extinguished March 2014
Debt Instrument [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity			475,000,000
Acquisition Notes [Member] | Non-interest bearing acquisition note, $5.0 million installment due March 2016
Debt Instrument [Line Items]
Debt instrument, aggregate principal amount			5,000,000
Debt Instrument Amount Of Installment			5,000,000.0
Long-term debt			4,924,000	4,623,000
Term loan facility borrowings due March 2019, weighted-average interest rate of 2.41% at December 31, 2014, extinguished April 2015
Debt Instrument [Line Items]
Interest expense			$ 400,000
STARS [Member]
Debt Instrument [Line Items]
Payments to acquire interest in joint venture		$ 20,000,000
STARS [Member] | Acquisition Notes [Member] | Non-interest bearing acquisition note, $5.0 million installment due March 2016
Debt Instrument [Line Items]
Debt instrument, aggregate principal amount		$ 15,000,000
Debt Instrument, Number of Installment Payments | Installments			3
Debt Instrument Amount Of Installment			$ 5,000,000
Guarantor Subsidiaries [Member]
Debt Instrument [Line Items]
Noncontrolling interest, ownership percentage by parent			100.00%
Payments of Debt Issuance Costs			$ 0	0	10,436,000
Alternate Base Rate [Member] | Line of Credit [Member] | Credit Agreement [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate			0.75%
Adjusted LIBO [Member] | Line of Credit [Member] | Credit Agreement [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate			1.75%
Minimum [Member] | Revolving line of credit borrowings due May 2016, weighted-average interest rate of 1.9% at December 31, 2013, extinguished March 2014
Debt Instrument [Line Items]
Line of Credit Facility, Commitment Fee Percentage			0.25%
Minimum [Member] | Line of Credit [Member] | Credit Agreement [Member]
Debt Instrument [Line Items]
Debt Instrument, Debt Restrictive Covenants, Interest Coverage Ratio			3.00
Minimum [Member] | Alternate Base Rate [Member] | Line of Credit [Member] | Credit Agreement [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate			0.25%
Minimum [Member] | Alternate Base Rate [Member] | Line of Credit [Member] | Revolving Line of Credit April 2016 [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate			1.25%
Minimum [Member] | Adjusted LIBO [Member] | Line of Credit [Member] | Revolving Line of Credit April 2016 [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate			2.00%
Maximum [Member] | Revolving line of credit borrowings due May 2016, weighted-average interest rate of 1.9% at December 31, 2013, extinguished March 2014
Debt Instrument [Line Items]
Line of Credit Facility, Commitment Fee Percentage			0.40%
Maximum [Member] | Line of Credit [Member] | Credit Agreement [Member]
Debt Instrument [Line Items]
Debt covenants leverage ratio requirements			4.50
Maximum [Member] | Alternate Base Rate [Member] | Line of Credit [Member] | Credit Agreement [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate			1.00%
Other Current Assets [Member]
Debt Instrument [Line Items]
Payments of Debt Issuance Costs			$ 6,100,000
Interest Rate Swap [Member]
Debt Instrument [Line Items]
Derivative, Notional Amount											$ 500,000,000
Derivative, Fixed Interest Rate											1.57%
Remaining Balance Of Interest Rate Swap Notional Amount											$ 250,000,000
Swap [Member]
Debt Instrument [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax			(200,000)	(1,500,000)	$ 900,000
Fair Value, Measurements, Recurring [Member] | Interest Rate Swap [Member]
Debt Instrument [Line Items]
Derivative Liability			4,370,000	3,781,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Debt Instrument [Line Items]
Derivative Liability			$ 4,370,000	$ 3,781,000
Second Quarter 2016 [Member] | Line of Credit [Member] | Credit Agreement [Member]
Debt Instrument [Line Items]
Debt covenants leverage ratio requirements			4.25
Second Quarter 2017 [Member] | Line of Credit [Member] | Credit Agreement [Member]
Debt Instrument [Line Items]
Debt covenants leverage ratio requirements			4.00
Second Quarter 2018 [Member] | Line of Credit [Member] | Credit Agreement [Member]
Debt Instrument [Line Items]
Debt covenants leverage ratio requirements			3.50
Debt covenants, leverage ratio step up after qualified transaction, basis points			0.0025
Second Quarter 2019 [Member] | Line of Credit [Member] | Credit Agreement [Member]
Debt Instrument [Line Items]
Debt covenants, leverage ratio step down following a qualified transaction, basis points			0.25%
December 2017 [Member] | Interest Rate Swap [Member]
Debt Instrument [Line Items]
Quarterly Amortization of Interest Rate Swap Notional Amount											12,500,000
December 2018 [Member] | Interest Rate Swap [Member]
Debt Instrument [Line Items]
Quarterly Amortization of Interest Rate Swap Notional Amount											$ 25,000,000
Debt Instrument, Redemption, Period One [Member] | Notes Payable to Banks [Member] | 7.25% senior notes due June 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage Of Aggregate Principle Amount							103.63%	100.00%
Notes Payable to Banks [Member] | Notes Payable to Banks [Member] | 7.25% senior notes due June 2021 [Member]
Debt Instrument [Line Items]
Repurchase Price, Percentage of Principal Amount, Upon Certain Change of Control Events									101.00%
Debt Instrument, Repayments, Period One [Member] | Line of Credit [Member] | Term Loan Due March 2020 [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Periodic Payment	10,600,000
Debt Instrument, Repayments, Period Two [Member] | Line of Credit [Member] | Term Loan Due March 2020 [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Periodic Payment	21,300,000
Debt Instrument, Repayments, Period Three [Member] | Line of Credit [Member] | Term Loan Due March 2020 [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Periodic Payment	$ 31,900,000