Employee Benefit Plans - Additional Information (Details) $ in Thousands, £ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 GBP (£)	Mar. 31, 2015 USD ($)	Mar. 31, 2015 GBP (£)	Dec. 31, 2014 USD ($)	Jun. 30, 2012 USD ($) $ / £	Jun. 30, 2012 GBP (£) $ / £
Deferred Compensation Plan
Employee Benefit Plans Additional Information [Abstract]
Deferred Compensation Plan Assets	$ 5,000		$ 5,000
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 September 30, 2015, these investments totaled approximately $5 million. All gains and losses in these investments are materially offset by corresponding gains and losses in the Deferred Compensation Plan liabilities.
Pension Plan, Defined Benefit
Employee Benefit Plans Additional Information [Abstract]
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.
Net period benefit costs			$ 1,000	$ 1,000
Change in Plan Assets [Roll Forward]
Weighted average discount rate benefit obligations	3.95%		3.95%		3.95%
Estimated Future Pension Benefit Payments [Abstract]
Defined Benefit Plan Benefit Obligation, Outstanding Balance	$ 148,631		$ 148,631					$ 159,715
Pension Plan, Defined Benefit | Trust for Benefit of Employee
Estimated Future Pension Benefit Payments [Abstract]
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year, Description			During the second quarter of 2012, we adopted a payment plan with the trustees of the defined benefit plan, under which we would pay approximately British Pound (“GBP”) 2 million (approximately $3 million based on a USD:GBP exchange rate of 1.6:1) every year from 2012 through 2019. In the first quarter of 2015, based on the pension deficit, we adopted (as required every three years) an amended payment 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. This revised payment plan resulted in an increase of total required contributions from GBP 8 million to GBP 33 million (approximately $50 million at September 30, 2015).
Defined Benefit Plan, Expected Future Benefit Payments in Year One									$ 3,000	£ 2
Defined Benefit Plan, Expected Future Benefit Payments in Year Two									3,000	2
Defined Benefit Plan, Expected Future Benefit Payments in Year Three									3,000	2
Defined Benefit Plan, Expected Future Benefit Payments in Year Four									3,000	2
Defined Benefit Plan, Expected Future Benefit Payments in Year Five									3,000	2
Defined Benefit Plan, Expected Future Benefit Payments in Three Fiscal Years Thereafter									$ 3,000	£ 2
GBP:USD exchange rate | $ / £									0.625	0.625
Defined Benefit Plan Benefit Obligation, Outstanding Balance | £										£ 8
Pension Plan, Defined Benefit | Maximum
Employee Benefit Plans Additional Information [Abstract]
Net period benefit costs	1,000	$ 1,000
Amended Pension Plan, Defined Benefit | Trust for Benefit of Employee
Estimated Future Pension Benefit Payments [Abstract]
Defined Benefit Plan, Expected Future Benefit Payments in Year One						$ 3,000	£ 2
Defined Benefit Plan, Expected Future Benefit Payments in Year Two						3,000	2
Defined Benefit Plan, Expected Future Benefit Payments in Year Three						3,000	2
Defined Benefit Plan, Expected Future Benefit Payments in Year Four						3,000	2
Defined Benefit Plan, Expected Future Benefit Payments in Year Five						3,000	2
Defined Benefit Plan Expected Future Benefit Payments In Ten Fiscal Years Thereafter						$ 3,000	£ 2
Defined Benefit Plan Benefit Obligation, Outstanding Balance	$ 50,000		$ 50,000		£ 33