Intangible Assets Summary of Intangible Asset Account Activity (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Intangible Assets [Line Items]
Beginning balance, intangible assets, gross	$ 802,540	$ 749,194
Intangible assets acquired		43,400
Effect of change in exchange rates	(16,894)	(13,835)
Ending balance, intangible assets, gross	784,146	778,759
Customer contracts and relationships [Member] | Adjustment of Intangible Customer Relationship Asset Acquired [Member]
Intangible Assets [Line Items]
Intangible assets acquired	$ (1,500)