Employee Benefit Plans - Additional Information (Details) £ in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2016 USD ($) $ / £	Mar. 31, 2015 USD ($)	Mar. 31, 2015 GBP (£)
Deferred Compensation Plan
Defined Benefit Plan Disclosure [Line Items]
Deferred compensation arrangements, overall, description	We maintain a Non-Qualified Deferred Compensation Plan (the “Deferred Compensation Plan”) for executive officers, key employees and members of the Board of Directors. The Deferred Compensation Plan allows eligible participants to defer the receipt of eligible compensation, including equity awards, until designated future dates. We offset our obligations under the Deferred Compensation Plan by investing in the actual underlying investments. These investments are classified as trading securities and are carried at fair value. At March 31, 2016, these investments totaled approximately $5.5 million. All gains and losses in these investments are materially offset by corresponding gains and losses in the Deferred Compensation Plan liabilities.
Deferred compensation plan assets	$ 5.5
Pension Plan, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plans, general information	We have a contributory defined benefit plan that covers certain employees in the United Kingdom (“U.K.”). The net pension and supplemental retirement benefit obligations and the related periodic costs are based on, among other things, assumptions regarding the discount rate, estimated return on plan assets and mortality rates. These obligations and related periodic costs are measured using actuarial techniques and assumptions.
Defined benefit plan, pension, method to determine vested benefit obligation	The projected unit credit method is the actuarial cost method used to compute the pension liabilities and related expenses.
Weighted average discount rate benefit obligations	3.70%
Pension Plan, Defined Benefit | Trust for Benefit of Employee
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal year, Description	In the first quarter of 2015, based on the pension deficit, we adopted (as required every three years) an amended payment plan with the trustee of the defined benefit plan in which we will pay approximately GBP 2 million (approximately $3 million based on a USD:GBP exchange rate of 1.6:1) annually through 2030.)
GBP:USD exchange rate | $ / £	0.625
Pension Plan, Defined Benefit | Maximum
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit costs	$ 1.0	$ 1.0
Amended Pension Plan, Defined Benefit | Trust for Benefit of Employee
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, expected future benefit payments in year one		3.0	£ 2
Defined benefit plan, expected future benefit payments in year two		3.0	2
Defined benefit plan, expected future benefit payments in year three		3.0	2
Defined benefit plan, expected future benefit payments in year four		3.0	2
Defined benefit plan, expected future benefit payments in year five		3.0	2
Defined benefit plan, expected future benefit payments in ten fiscal years thereafter		$ 3.0	£ 2