Fair Value Measurement Narrative (Details)	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2015 USD ($) forward_exchange_contrtact	Sep. 30, 2015 USD ($) forward_exchange_contrtact	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2008 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale investments	$ 47,900,000	$ 47,900,000		$ 43,000,000
Purchases of available-for-sale investments	5,000,000	15,200,000	$ 6,600,000
Trading securities	$ 9,300,000	9,300,000		8,900,000
Purchase of trading securities related to deferred compensation plans		1,000,000	1,200,000
Proceeds from securities sold		$ 300,000	$ 300,000
Number of foreign exchange contracts held | forward_exchange_contrtact	30	30
Derivative, notional amount	$ 36,100,000.0	$ 36,100,000.0
Unrealized gain (loss) on interest rate lock, recorded in accumulated other comprehensive loss		(400,000)		(400,000)
Long-Term Debt	597,900,000	597,900,000		597,600,000
Long-term debt, fair value	637,300,000	637,300,000		645,100,000
Interest Rate Lock 2010
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized gain (loss) on interest rate lock, recorded in accumulated other comprehensive loss					$ (1,600,000)
Interest Rate Lock 2008
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized gain (loss) on interest rate lock, recorded in accumulated other comprehensive loss						$ 1,200,000
Quoted Prices in Active Markets for Similar Assets (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale investments	43,100,000	43,100,000		43,000,000
Trading securities	0	0		0
Unobservable inputs for which little or no market data exists (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale investments	4,800,000	4,800,000		0
Trading securities	$ 0	$ 0		$ 0