Income Taxes Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Operating Loss Carryforwards [Line Items]
Unrecognized tax benefits, period increase (decrease)			$ 108	$ 3,866
Income tax expense	$ 1,136	$ 3,326	$ 3,533	$ 7,537
Document Period End Date			Jun. 30, 2015
UNITED KINGDOM
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 41,300		$ 41,300