Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Mar. 31, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Taxes
Effective tax rate (as a percent)	26.80%		25.50%	26.60%	26.30%
Tax benefit primarily related to the completion of prior audits					$ 3,645
Tax cost primarily related to delay of research and development credits and certain domestic taxes on foreign income that are part of tax provisions within American Taxpayer Relief Act			11,300
Effective tax rate before adjustments (as a percent)	26.50%	23.90%		26.50%	23.90%
Liability for unrecognized tax benefits, including penalties and interest, which if recognized would impact the effective tax rate	18,469			18,469
Unrecognized tax benefits, anticipated adjustment for changing facts and circumstances, over the next twelve month period	$ 2,536			$ 2,536