Debt - Narrative (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Ohio Department of Development Term Loan	$ 2,109	$ 2,428
Line of Credit, Current Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity	300,000
Line Of Credit Facility Maximum Borrowing Capacity	400,000
Line Of Credit Maturity Date	2018-06
Line of Credit Facility, Covenant Compliance	As of December 31, 2014 and December 31, 2013, the Company’s consolidated leverage ratio was below 1.0 to 1 and the Company was also in compliance with all of the facilities’ other covenants
Line of Credit Facility, Covenant Terms	The maximum amount available under this facility can be increased to $400,000 at the Company’s option if the lenders agree and the Company satisfies certain conditions. Access to this facility is dependent on meeting certain financial, acquisition and other covenants, but primarily depends on the Company’s consolidated leverage ratio calculation, which cannot exceed 3.50 to 1.
Long-term Debt, Weighted Average Interest Rate	1.16%
Ohio Department Of Development [Member]
Debt Instrument [Line Items]
Debt Instrument Maturity Year	2021
Ohio Department of Development Term Loan	$ 3,500
Principal Repayment Commencement Date	2010-09
Debt Instrument Interest Rate Stated Percentage	2.00%
Debt Instrument Interest Rate Stated Percentage In Year Five	3.00%