Commitments and Contingencies (Details) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2012 Pending or Threatened Litigation [Member] USD ($)	Dec. 31, 2012 Pending or Threatened Litigation [Member] GBP (£)
Leases [Abstract]
Operating Leases, Rent Expense	$ 13,464	$ 19,678	$ 20,179
Operating Leases, Future Minimum Payments, Due 2013	11,682
Operating Leases, Future Minimum Payments, Due 2014	7,637
Operating Leases, Future Minimum Payments, Due 2015	4,570
Operating Leases, Future Minimum Payments, Due 2016	2,240
Operating Leases, Future Minimum Payments, Due 2017	1,297
Operating Leases, Future Minimum Payments, Due Thereafter	3,523
Loss Contingencies [Line Items]
Damages sought, amount				8,893	5,500
Damages sought, interest at statutory rate (per annum)				8.00%	8.00%
IRS proposed adjustments to tax years 2000 through 2002, before penalty and interest	$ 16,500
Potential penalty, percentage of tax assessment	20.00%