Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Income Taxes [Abstract]
Income Tax Expense (Benefit)	$ 3,762	$ 2,205
Effective tax rate (in hundredths)	24.80%
Income tax reconciliation, change in tax laws	(1,300)
Income tax reconciliation, sale of office building	1,500
Maximum [Member]
Income Tax Contingency [Line Items]
Potential future increase/(decrease) to unrecognized tax benefits	8,000
Minimum [Member]
Income Tax Contingency [Line Items]
Potential future increase/(decrease) to unrecognized tax benefits	(6,000)
Non-US Jurisdiction [Member]
Income Tax Contingency [Line Items]
Number of formal assessments	2
Amount in which the reserve for unrecognized tax benefits changed due to foreign currency translation	177
Increase/(Decrease) in reserve for unrecognized tax benefits	$ (139)