Income Taxes (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Income Taxes
Effective tax rate (as a percent)	26.40%	20.90%
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
Tax benefit per diluted common share 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 (in dollars per share)		$ 0.07
Effective tax rate before adjustments (as a percent)	26.50%	26.80%
Liability for unrecognized tax benefits, including penalties and interest, which if recognized would impact the effective tax rate	15,628
Unrecognized tax benefits, anticipated adjustment for changing facts and circumstances, over the next twelve month period	$ 2,732