Restructuring Charges (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Changes in restructuring liabilities, recorded in other accrued expenses
Restructuring credit	$ 61		$ (102)
2014 Plan
Restructuring Charges
Expected number of employees to be impacted by the restructuring	280
Changes in restructuring liabilities, recorded in other accrued expenses
Restructuring liability, as of January 1, 2015	16,352
Restructuring credit	25
Expected restructuring charges	26,939
Cash paid	(5,392)
Foreign exchange rate changes	(627)
Restructuring liability, as of March 31, 2015	10,358
Restructuring charges, incurred to date	24,492
2014 Plan | North America
Changes in restructuring liabilities, recorded in other accrued expenses
Restructuring credit	0
Expected restructuring charges	1,011
Restructuring charges, incurred to date	1,011
2014 Plan | International
Changes in restructuring liabilities, recorded in other accrued expenses
Restructuring credit	0
Expected restructuring charges	18,400
Restructuring charges, incurred to date	17,831
2014 Plan | Other
Changes in restructuring liabilities, recorded in other accrued expenses
Restructuring credit	25
Expected restructuring charges	339
Restructuring charges, incurred to date	339
2014 Plan | Corporate
Changes in restructuring liabilities, recorded in other accrued expenses
Restructuring credit	0
Expected restructuring charges	7,189
Restructuring charges, incurred to date	5,311
2014 Plan | Employee Severance [Member]
Changes in restructuring liabilities, recorded in other accrued expenses
Restructuring liability, as of January 1, 2015	15,152
Restructuring credit	25
Expected restructuring charges	20,000
Cash paid	(4,192)
Foreign exchange rate changes	(627)
Restructuring liability, as of March 31, 2015	10,358
2014 Plan | Office Closures
Changes in restructuring liabilities, recorded in other accrued expenses
Restructuring liability, as of January 1, 2015	1,200
Restructuring credit	0
Expected restructuring charges	7,000
Cash paid	(1,200)
Foreign exchange rate changes	0
Restructuring liability, as of March 31, 2015	0
2012 Plan
Changes in restructuring liabilities, recorded in other accrued expenses
Restructuring credit	36
Restructuring charges, incurred to date	13,985	[1]
2012 Plan | North America
Changes in restructuring liabilities, recorded in other accrued expenses
Restructuring credit	1
Restructuring charges, incurred to date	1,703	[1]
2012 Plan | International
Changes in restructuring liabilities, recorded in other accrued expenses
Restructuring credit	0
Restructuring charges, incurred to date	8,851	[1]
2012 Plan | Corporate
Changes in restructuring liabilities, recorded in other accrued expenses
Restructuring credit	35	[2]
Restructuring charges, incurred to date	3,431	[1],[2]
2012 Plan | Facility Closing [Member]
Changes in restructuring liabilities, recorded in other accrued expenses
Restructuring liability, as of January 1, 2015	1,694
Restructuring credit	36
Cash paid	(403)
Foreign exchange rate changes	(17)
Restructuring liability, as of March 31, 2015	$ 1,310

[1] Our restructuring charges, particularly lease-related office closure costs, are subject to estimate. If we are unable to find tenants for vacated offices or sub-lease terms are different from our assumptions, our actual restructuring charges will differ from our current estimates.

[2] Corporate restructuring charges include costs for administrative facility consolidation.