Restructuring Charges - Changes in Restructuring Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Changes in restructuring liabilities, recorded in other accrued expenses
Restructuring charge	$ 1,002	$ 21,244	$ 1,738	$ 22,650
2014 Plan
Changes in restructuring liabilities, recorded in other accrued expenses
Restructuring liability, as of January 1, 2015			16,352
Restructuring charge	469		1,126
Non-cash items			(250)
Cash paid			(11,957)
Foreign exchange rate changes			(836)
Restructuring liability, as of September 30, 2015	4,435		4,435
2014 Plan | Employee Severance and Termination
Changes in restructuring liabilities, recorded in other accrued expenses
Restructuring liability, as of January 1, 2015			15,152
Restructuring charge			499
Non-cash items			(205)
Cash paid			(10,735)
Foreign exchange rate changes			(836)
Restructuring liability, as of September 30, 2015	3,875		3,875
2014 Plan | Professional Fees, Office Closures and Other
Changes in restructuring liabilities, recorded in other accrued expenses
Restructuring liability, as of January 1, 2015			1,200
Restructuring charge			627
Non-cash items			(45)
Cash paid			(1,222)
Foreign exchange rate changes			0
Restructuring liability, as of September 30, 2015	560		560
2012 Plan
Changes in restructuring liabilities, recorded in other accrued expenses
Restructuring charge	13		81
2012 Plan | Office Closures
Changes in restructuring liabilities, recorded in other accrued expenses
Restructuring liability, as of January 1, 2015			1,694
Restructuring charge			81
Non-cash items			(1)
Cash paid			(845)
Foreign exchange rate changes			(11)
Restructuring liability, as of September 30, 2015	$ 918		$ 918