Retirement Plans (Details) - UK plans (UK Plans, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 9,483	$ 9,094
Number of members in the plan	90
Accrued pension liability	4,500
Period over which the deficit is being funded	10 years
Contribution rates, employer	24.60%
Contribution rates, employee	3.00%
Active members
Defined Benefit Plan Disclosure [Line Items]
Number of members in the plan	55
Transferred to defined contribution plan
Defined Benefit Plan Disclosure [Line Items]
Number of members in the plan	6
Accrued pension liability	3,500	3,300
Still employed by company
Defined Benefit Plan Disclosure [Line Items]
Number of members in the plan	5
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets	6.80%	7.00%
Fair value of plan assets	6,149	6,351
Gilts
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets	3.00%	4.00%
Fair value of plan assets	1,700	1,350
Corporate
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets	4.70%	5.50%
Fair value of plan assets	1,566	1,381
Other (cash)
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets	3.50%	4.00%
Fair value of plan assets	$ 68	$ 12